diff --git a/README.md b/README.md
index 9df2ed4..f26b1ff 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Implements the TopoJSON specification:
 https://github.com/mbostock/topojson-specification
 
 Uses the GeoJSON implementation of paulmach:
-https://github.com/paulmach/go.geojson
+https://github.com/paulmach/orb/geojson
 
 Large parts are a port of the canonical JavaScript implementation, big chunks
 of the test suite are ported as well:
diff --git a/bounds.go b/bounds.go
index 60052f2..687ab2f 100644
--- a/bounds.go
+++ b/bounds.go
@@ -3,7 +3,7 @@ package topojson
 import (
 	"math"
 
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb"
 )
 
 func (t *Topology) bounds() {
@@ -20,25 +20,45 @@ func (t *Topology) bounds() {
 
 }
 
-func (t *Topology) boundGeometry(g *geojson.Geometry) {
-	switch g.Type {
-	case geojson.GeometryCollection:
-		for _, geom := range g.Geometries {
-			t.boundGeometry(geom)
+func (t *Topology) boundGeometry(g orb.Geometry) {
+	switch c := g.(type) {
+	case orb.Point:
+		t.BBox(c.Bound())
+	case orb.MultiPoint:
+		t.BBox(c.Bound())
+	case orb.LineString:
+		t.BBox(c.Bound())
+	case orb.MultiLineString:
+		t.BBox(c.Bound())
+	case orb.Polygon:
+		t.BBox(c.Bound())
+	case orb.MultiPolygon:
+		t.BBox(c.Bound())
+	case orb.Collection:
+		t.BBox(c.Bound())
+		// for _, geo := range c {
+		// 	t.boundGeometry(geo)
+		// }
+	}
+}
+
+func (t *Topology) BBox(b orb.Bound) {
+	xx := []float64{b.Min[0], b.Max[0]}
+	yy := []float64{b.Min[1], b.Max[1]}
+	for _, x := range xx {
+		if x < t.BoundingBox[0] {
+			t.BoundingBox[0] = x
+		}
+		if x > t.BoundingBox[2] {
+			t.BoundingBox[2] = x
+		}
+	}
+	for _, y := range yy {
+		if y < t.BoundingBox[1] {
+			t.BoundingBox[1] = y
 		}
-	case geojson.GeometryPoint:
-		t.boundPoint(g.Point)
-	case geojson.GeometryMultiPoint:
-		t.boundPoints(g.MultiPoint)
-	case geojson.GeometryLineString:
-		t.boundPoints(g.LineString)
-	case geojson.GeometryMultiLineString:
-		t.boundMultiPoints(g.MultiLineString)
-	case geojson.GeometryPolygon:
-		t.boundMultiPoints(g.Polygon)
-	case geojson.GeometryMultiPolygon:
-		for _, poly := range g.MultiPolygon {
-			t.boundMultiPoints(poly)
+		if y > t.BoundingBox[3] {
+			t.BoundingBox[3] = y
 		}
 	}
 }
diff --git a/bounds_test.go b/bounds_test.go
index dee9f79..135afb8 100644
--- a/bounds_test.go
+++ b/bounds_test.go
@@ -4,19 +4,20 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	geojson "github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	geojson "github.com/paulmach/orb/geojson"
 )
 
 func TestBoundingBox(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("bar", geojson.NewLineStringGeometry([][]float64{
-			{-1, 0}, {1, 0}, {-2, 3},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("bar", orb.LineString{
+			orb.Point{-1, 0}, orb.Point{1, 0}, orb.Point{-2, 3},
+		}),
 	}
 
 	topo := &Topology{input: in}
diff --git a/cut_test.go b/cut_test.go
index 87e55a7..5cc6f96 100644
--- a/cut_test.go
+++ b/cut_test.go
@@ -5,7 +5,8 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	"github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
 // See https://github.com/mbostock/topojson/blob/master/test/topology/cut-test.js
@@ -15,12 +16,12 @@ func TestCutDuplicates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abc2", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abc2", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -28,13 +29,13 @@ func TestCutDuplicates(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc2")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 5)
 	is.Nil(o2.Arc.Next)
@@ -45,12 +46,12 @@ func TestCutReversedDuplicates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -58,13 +59,13 @@ func TestCutReversedDuplicates(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "cba")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 5)
 	is.Nil(o2.Arc.Next)
@@ -75,16 +76,16 @@ func TestCutDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("abca2", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		}),
+		NewTestFeature("abca2", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -92,14 +93,14 @@ func TestCutDuplicateRings(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "abca2")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -111,16 +112,16 @@ func TestCutReversedDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("acba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {2, 0}, {1, 0}, {0, 0},
+		}),
+		NewTestFeature("acba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -128,14 +129,14 @@ func TestCutReversedDuplicateRings(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "acba")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -147,16 +148,16 @@ func TestCutRotatedDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bcab", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {0, 0}, {1, 0},
+		}),
+		NewTestFeature("bcab", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -164,14 +165,14 @@ func TestCutRotatedDuplicateRings(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "bcab")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -183,14 +184,14 @@ func TestCutRingLine(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcaLine", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
-		NewTestFeature("abcaPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abcaLine", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abcaPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -198,13 +199,13 @@ func TestCutRingLine(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcaLine")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abcaPolygon")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -216,14 +217,14 @@ func TestCutRingLineReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcaLine", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
-		NewTestFeature("bcabPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {0, 0}, {1, 0},
+		NewTestFeature("abcaLine", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("bcabPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -231,13 +232,13 @@ func TestCutRingLineReversed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcaLine")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "bcabPolygon")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -249,14 +250,14 @@ func TestCutRingLineReversed2(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("bcabLine", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0}, {0, 0}, {1, 0},
-		})),
-		NewTestFeature("abcaPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("bcabLine", orb.LineString{
+			orb.Point{1, 0}, {2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
+		}),
+		NewTestFeature("abcaPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -264,13 +265,13 @@ func TestCutRingLineReversed2(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "bcabLine")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abcaPolygon")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -282,12 +283,12 @@ func TestCutOldArcExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -295,7 +296,7 @@ func TestCutOldArcExtends(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -303,7 +304,7 @@ func TestCutOldArcExtends(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "ab")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Nil(o2.Arc.Next)
@@ -314,12 +315,12 @@ func TestCutReversedOldArcExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -327,7 +328,7 @@ func TestCutReversedOldArcExtends(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -335,7 +336,7 @@ func TestCutReversedOldArcExtends(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "ab")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Nil(o2.Arc.Next)
@@ -346,12 +347,12 @@ func TestCutNewArcSharesStart(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ade", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 1}, {2, 1},
-		})),
+		NewTestFeature("ade", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 1}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -359,13 +360,13 @@ func TestCutNewArcSharesStart(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "ade")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 5)
 	is.Nil(o2.Arc.Next)
@@ -376,11 +377,11 @@ func TestCutRingNoCuts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("aba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 0},
+		NewTestFeature("aba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -388,7 +389,7 @@ func TestCutRingNoCuts(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "aba")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 2)
@@ -400,11 +401,11 @@ func TestCutRingAANoCuts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("aa", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0, 0},
+		NewTestFeature("aa", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -412,7 +413,7 @@ func TestCutRingAANoCuts(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "aa")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 1)
@@ -424,11 +425,11 @@ func TestCutRingANoCuts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("a", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0},
+		NewTestFeature("a", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -436,7 +437,7 @@ func TestCutRingANoCuts(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "a")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 0)
@@ -448,12 +449,12 @@ func TestCutNewLineSharesEnd(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dec", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 1}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dec", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 1}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -461,13 +462,13 @@ func TestCutNewLineSharesEnd(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "dec")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 5)
 	is.Nil(o2.Arc.Next)
@@ -478,12 +479,12 @@ func TestCutNewLineExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -491,13 +492,13 @@ func TestCutNewLineExtends(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "ab")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 2)
 	is.Equal(o2.Arc.End, 3)
 	is.Equal(o2.Arc.Next.Start, 3)
@@ -510,12 +511,12 @@ func TestCutNewLineExtendsReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ba", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {0, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("ba", orb.LineString{
+			orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -523,13 +524,13 @@ func TestCutNewLineExtendsReversed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "ba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 2)
 	is.Equal(o2.Arc.End, 3)
 	is.Equal(o2.Arc.Next.Start, 3)
@@ -542,12 +543,12 @@ func TestCutNewStartsMiddle(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("bc", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("bc", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -555,7 +556,7 @@ func TestCutNewStartsMiddle(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -563,7 +564,7 @@ func TestCutNewStartsMiddle(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "bc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Nil(o2.Arc.Next)
@@ -574,12 +575,12 @@ func TestCutNewStartsMiddleReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("bc", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("bc", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -587,7 +588,7 @@ func TestCutNewStartsMiddleReversed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -595,7 +596,7 @@ func TestCutNewStartsMiddleReversed(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "bc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Nil(o2.Arc.Next)
@@ -606,12 +607,12 @@ func TestCutNewLineDeviates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -619,7 +620,7 @@ func TestCutNewLineDeviates(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -627,7 +628,7 @@ func TestCutNewLineDeviates(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "abd")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -640,12 +641,12 @@ func TestCutNewLineDeviatesReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("abd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -653,7 +654,7 @@ func TestCutNewLineDeviatesReversed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -661,7 +662,7 @@ func TestCutNewLineDeviatesReversed(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "abd")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -674,12 +675,12 @@ func TestCutNewLineMerges(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dbc", geojson.NewLineStringGeometry([][]float64{
-			{3, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dbc", orb.LineString{
+			orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -687,7 +688,7 @@ func TestCutNewLineMerges(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -695,7 +696,7 @@ func TestCutNewLineMerges(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "dbc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -708,12 +709,12 @@ func TestCutNewLineMergesReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("dbc", geojson.NewLineStringGeometry([][]float64{
-			{3, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("dbc", orb.LineString{
+			orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -721,7 +722,7 @@ func TestCutNewLineMergesReversed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -729,7 +730,7 @@ func TestCutNewLineMergesReversed(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "dbc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -742,12 +743,12 @@ func TestCutNewLineSharesMidpoint(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 0}, {2, 1},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dbe", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -755,7 +756,7 @@ func TestCutNewLineSharesMidpoint(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -763,7 +764,7 @@ func TestCutNewLineSharesMidpoint(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "dbe")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -776,12 +777,12 @@ func TestCutNewLineSkipsPoint(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcde", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0},
-		})),
-		NewTestFeature("adbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abcde", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
+		NewTestFeature("adbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -789,7 +790,7 @@ func TestCutNewLineSkipsPoint(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcde")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	o1Next := o1.Arc.Next
@@ -800,7 +801,7 @@ func TestCutNewLineSkipsPoint(t *testing.T) {
 	is.Nil(o1Next.Next.Next)
 
 	o2 := GetFeature(topo, "adbe")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 5)
 	is.Equal(o2.Arc.End, 6)
 	o2Next := o2.Arc.Next
@@ -816,12 +817,12 @@ func TestCutNewLineSkipsPointReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("edcba", geojson.NewLineStringGeometry([][]float64{
-			{4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("adbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("edcba", orb.LineString{
+			orb.Point{4, 0}, orb.Point{3, 0}, orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("adbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -829,7 +830,7 @@ func TestCutNewLineSkipsPointReversed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "edcba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	o1Next := o1.Arc.Next
@@ -840,7 +841,7 @@ func TestCutNewLineSkipsPointReversed(t *testing.T) {
 	is.Nil(o1Next.Next.Next)
 
 	o2 := GetFeature(topo, "adbe")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 5)
 	is.Equal(o2.Arc.End, 6)
 	o2Next := o2.Arc.Next
@@ -856,9 +857,9 @@ func TestCutSelfIntersectsMiddle(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {1, 0}, {4, 0},
-		})),
+		NewTestFeature("abcdbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -866,7 +867,7 @@ func TestCutSelfIntersectsMiddle(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcdbe")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 5)
 	is.Nil(o1.Arc.Next)
@@ -877,9 +878,9 @@ func TestCutSelfIntersectsStart(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abacd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abacd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -887,7 +888,7 @@ func TestCutSelfIntersectsStart(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abacd")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Equal(o1.Arc.Next.Start, 2)
@@ -900,9 +901,9 @@ func TestCutSelfIntersectsEnd(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {4, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abcdbd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{4, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -910,7 +911,7 @@ func TestCutSelfIntersectsEnd(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcdbd")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Equal(o1.Arc.Next.Start, 2)
@@ -923,12 +924,12 @@ func TestCutSelfIntersectsShares(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {1, 0}, {4, 0},
-		})),
-		NewTestFeature("fbg", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 0}, {2, 1},
-		})),
+		NewTestFeature("abcdbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{4, 0},
+		}),
+		NewTestFeature("fbg", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -936,7 +937,7 @@ func TestCutSelfIntersectsShares(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcdbe")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	o1Next := o1.Arc.Next
@@ -947,7 +948,7 @@ func TestCutSelfIntersectsShares(t *testing.T) {
 	is.Nil(o1Next.Next.Next)
 
 	o2 := GetFeature(topo, "fbg")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 6)
 	is.Equal(o2.Arc.End, 7)
 	is.Equal(o2.Arc.Next.Start, 7)
@@ -960,9 +961,9 @@ func TestCutLineClosed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		})),
+		NewTestFeature("abca", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -970,7 +971,7 @@ func TestCutLineClosed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
@@ -981,11 +982,11 @@ func TestCutRingClosed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -993,7 +994,7 @@ func TestCutRingClosed(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
@@ -1005,16 +1006,16 @@ func TestCutDuplicateRingsShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("abca2", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		}),
+		NewTestFeature("abca2", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1022,14 +1023,14 @@ func TestCutDuplicateRingsShare(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "abca2")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -1041,16 +1042,16 @@ func TestCutDuplicateRingsReversedShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("acba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0, 1}, {1, 0}, {0, 0},
+		}),
+		NewTestFeature("acba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1058,14 +1059,14 @@ func TestCutDuplicateRingsReversedShare(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "acba")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -1077,16 +1078,16 @@ func TestCutCoincidentRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bcab", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {0, 1}, {0, 0}, {1, 0},
+		}),
+		NewTestFeature("bcab", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1094,14 +1095,14 @@ func TestCutCoincidentRings(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "bcab")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -1113,16 +1114,16 @@ func TestCutCoincidentRings2(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bacb", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {0, 0}, {0, 1}, {1, 0},
+		}),
+		NewTestFeature("bacb", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{0, 0}, orb.Point{0, 1}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1130,14 +1131,14 @@ func TestCutCoincidentRings2(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "bacb")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -1149,21 +1150,21 @@ func TestCutCoincidentRings3(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcda", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0},
+		NewTestFeature("abcda", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{1, 1}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("efae", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, -1}, {1, -1}, {0, 0}, {0, -1},
+		}),
+		NewTestFeature("efae", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, -1}, orb.Point{1, -1}, orb.Point{0, 0}, orb.Point{0, -1},
 			},
-		})),
-		NewTestFeature("ghcg", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 2}, {1, 2}, {1, 1}, {0, 2},
+		}),
+		NewTestFeature("ghcg", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 2}, orb.Point{1, 2}, orb.Point{1, 1}, orb.Point{0, 2},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1171,7 +1172,7 @@ func TestCutCoincidentRings3(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcda")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 2)
@@ -1180,14 +1181,14 @@ func TestCutCoincidentRings3(t *testing.T) {
 	is.Nil(o1.Arcs[0].Next.Next)
 
 	o2 := GetFeature(topo, "efae")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 5)
 	is.Equal(o2.Arcs[0].End, 8)
 	is.Nil(o2.Arcs[0].Next)
 
 	o3 := GetFeature(topo, "ghcg")
-	is.Equal(o3.Type, geojson.GeometryPolygon)
+	is.Equal(o3.Type, geojson.TypePolygon)
 	is.Equal(len(o3.Arcs), 1)
 	is.Equal(o3.Arcs[0].Start, 9)
 	is.Equal(o3.Arcs[0].End, 12)
@@ -1199,16 +1200,16 @@ func TestCutNoCutsButRotated(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("dbed", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{2, 1}, {1, 0}, {2, 2}, {2, 1},
+		}),
+		NewTestFeature("dbed", orb.Polygon{
+			orb.Ring{
+				orb.Point{2, 1}, orb.Point{1, 0}, orb.Point{2, 2}, orb.Point{2, 1},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1216,14 +1217,14 @@ func TestCutNoCutsButRotated(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "dbed")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -1242,16 +1243,16 @@ func TestCutOverlapping(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcda", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0}, // rotated to BCDAB, cut BC-CDAB
+		NewTestFeature("abcda", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{1, 1}, orb.Point{0, 1}, orb.Point{0, 0}, // rotated to BCDAB, cut BC-CDAB
 			},
-		})),
-		NewTestFeature("befcb", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {2, 1}, {1, 1}, {1, 0},
+		}),
+		NewTestFeature("befcb", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{2, 1}, orb.Point{1, 1}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1259,7 +1260,7 @@ func TestCutOverlapping(t *testing.T) {
 	topo.cut()
 
 	o1 := GetFeature(topo, "abcda")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 1)
@@ -1268,7 +1269,7 @@ func TestCutOverlapping(t *testing.T) {
 	is.Nil(o1.Arcs[0].Next.Next)
 
 	o2 := GetFeature(topo, "befcb")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 5)
 	is.Equal(o2.Arcs[0].End, 8)
diff --git a/dedup_test.go b/dedup_test.go
index d264071..ae55dcf 100644
--- a/dedup_test.go
+++ b/dedup_test.go
@@ -5,7 +5,8 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	"github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
 // See https://github.com/mbostock/topojson/blob/master/test/topology/dedup-test.js
@@ -15,12 +16,12 @@ func TestDedupDuplicates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abc2", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abc2", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -29,13 +30,13 @@ func TestDedupDuplicates(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc2")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 0)
 	is.Equal(o2.Arc.End, 2)
 	is.Nil(o2.Arc.Next)
@@ -46,12 +47,12 @@ func TestDedupReversedDuplicates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -60,13 +61,13 @@ func TestDedupReversedDuplicates(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "cba")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 2)
 	is.Equal(o2.Arc.End, 0)
 	is.Nil(o2.Arc.Next)
@@ -77,16 +78,16 @@ func TestDedupDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("abca2", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		}),
+		NewTestFeature("abca2", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -95,14 +96,14 @@ func TestDedupDuplicateRings(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "abca2")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -114,16 +115,16 @@ func TestDedupReversedDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("acba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {2, 0}, {1, 0}, {0, 0},
+		}),
+		NewTestFeature("acba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -132,14 +133,14 @@ func TestDedupReversedDuplicateRings(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "acba")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 3)
 	is.Equal(o2.Arcs[0].End, 0)
@@ -151,16 +152,16 @@ func TestDedupRotatedDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bcab", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {0, 0}, {1, 0},
+		}),
+		NewTestFeature("bcab", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -169,14 +170,14 @@ func TestDedupRotatedDuplicateRings(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "bcab")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -188,14 +189,14 @@ func TestDedupRingLine(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcaLine", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
-		NewTestFeature("abcaPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abcaLine", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abcaPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -204,13 +205,13 @@ func TestDedupRingLine(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcaLine")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abcaPolygon")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -222,14 +223,14 @@ func TestDedupRingLineReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcaLine", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
-		NewTestFeature("bcabPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {0, 0}, {1, 0},
+		NewTestFeature("abcaLine", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("bcabPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -238,13 +239,13 @@ func TestDedupRingLineReversed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcaLine")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "bcabPolygon")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -260,14 +261,14 @@ func TestDedupRingLineReversed2(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("bcabLine", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0}, {0, 0}, {1, 0},
-		})),
-		NewTestFeature("abcaPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("bcabLine", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
+		}),
+		NewTestFeature("abcaPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -276,13 +277,13 @@ func TestDedupRingLineReversed2(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "bcabLine")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abcaPolygon")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -294,12 +295,12 @@ func TestDedupOldArcExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -308,7 +309,7 @@ func TestDedupOldArcExtends(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -316,7 +317,7 @@ func TestDedupOldArcExtends(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "ab")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 0)
 	is.Equal(o2.Arc.End, 1)
 	is.Nil(o2.Arc.Next)
@@ -327,12 +328,12 @@ func TestDedupReversedOldArcExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -341,7 +342,7 @@ func TestDedupReversedOldArcExtends(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -349,7 +350,7 @@ func TestDedupReversedOldArcExtends(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "ab")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 2)
 	is.Equal(o2.Arc.End, 1)
 	is.Nil(o2.Arc.Next)
@@ -360,12 +361,12 @@ func TestDedupNewArcSharesStart(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ade", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 1}, {2, 1},
-		})),
+		NewTestFeature("ade", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 1}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -374,13 +375,13 @@ func TestDedupNewArcSharesStart(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "ade")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 5)
 	is.Nil(o2.Arc.Next)
@@ -391,11 +392,11 @@ func TestDedupRingNoCuts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("aba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 0},
+		NewTestFeature("aba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -404,7 +405,7 @@ func TestDedupRingNoCuts(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "aba")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 2)
@@ -416,11 +417,11 @@ func TestDedupRingAANoCuts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("aa", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0, 0},
+		NewTestFeature("aa", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -429,7 +430,7 @@ func TestDedupRingAANoCuts(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "aa")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 1)
@@ -441,11 +442,11 @@ func TestDedupRingANoCuts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("a", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0},
+		NewTestFeature("a", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -454,7 +455,7 @@ func TestDedupRingANoCuts(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "a")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 0)
@@ -466,12 +467,12 @@ func TestDedupNewLineSharesEnd(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dec", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 1}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dec", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 1}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -480,13 +481,13 @@ func TestDedupNewLineSharesEnd(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "dec")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 5)
 	is.Nil(o2.Arc.Next)
@@ -497,12 +498,12 @@ func TestDedupNewLineExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -511,13 +512,13 @@ func TestDedupNewLineExtends(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "ab")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 0)
 	is.Equal(o2.Arc.End, 1)
 	is.Equal(o2.Arc.Next.Start, 3)
@@ -530,12 +531,12 @@ func TestDedupNewLineExtendsReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ba", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {0, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("ba", orb.LineString{
+			orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -544,13 +545,13 @@ func TestDedupNewLineExtendsReversed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "ba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Nil(o1.Arc.Next)
 
 	o2 := GetFeature(topo, "abc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 1)
 	is.Equal(o2.Arc.End, 0)
 	is.Equal(o2.Arc.Next.Start, 3)
@@ -563,12 +564,12 @@ func TestDedupNewStartsMiddle(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("bc", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("bc", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -577,7 +578,7 @@ func TestDedupNewStartsMiddle(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -585,7 +586,7 @@ func TestDedupNewStartsMiddle(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "bc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 1)
 	is.Equal(o2.Arc.End, 2)
 	is.Nil(o2.Arc.Next)
@@ -596,12 +597,12 @@ func TestDedupNewStartsMiddleReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("bc", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("bc", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -610,7 +611,7 @@ func TestDedupNewStartsMiddleReversed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -618,7 +619,7 @@ func TestDedupNewStartsMiddleReversed(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "bc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 1)
 	is.Equal(o2.Arc.End, 0)
 	is.Nil(o2.Arc.Next)
@@ -629,12 +630,12 @@ func TestDedupNewLineDeviates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -643,7 +644,7 @@ func TestDedupNewLineDeviates(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -651,7 +652,7 @@ func TestDedupNewLineDeviates(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "abd")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 0)
 	is.Equal(o2.Arc.End, 1)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -664,12 +665,12 @@ func TestDedupNewLineDeviatesReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("abd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -678,7 +679,7 @@ func TestDedupNewLineDeviatesReversed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -686,7 +687,7 @@ func TestDedupNewLineDeviatesReversed(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "abd")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 2)
 	is.Equal(o2.Arc.End, 1)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -699,12 +700,12 @@ func TestDedupNewLineMerges(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dbc", geojson.NewLineStringGeometry([][]float64{
-			{3, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dbc", orb.LineString{
+			orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -713,7 +714,7 @@ func TestDedupNewLineMerges(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -721,7 +722,7 @@ func TestDedupNewLineMerges(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "dbc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 1)
@@ -734,12 +735,12 @@ func TestDedupNewLineMergesReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("dbc", geojson.NewLineStringGeometry([][]float64{
-			{3, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("dbc", orb.LineString{
+			orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -748,7 +749,7 @@ func TestDedupNewLineMergesReversed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "cba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -756,7 +757,7 @@ func TestDedupNewLineMergesReversed(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "dbc")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 1)
@@ -769,12 +770,12 @@ func TestDedupNewLineSharesMidpoint(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 0}, {2, 1},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dbe", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -783,7 +784,7 @@ func TestDedupNewLineSharesMidpoint(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abc")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	is.Equal(o1.Arc.Next.Start, 1)
@@ -791,7 +792,7 @@ func TestDedupNewLineSharesMidpoint(t *testing.T) {
 	is.Nil(o1.Arc.Next.Next)
 
 	o2 := GetFeature(topo, "dbe")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 3)
 	is.Equal(o2.Arc.End, 4)
 	is.Equal(o2.Arc.Next.Start, 4)
@@ -804,12 +805,12 @@ func TestDedupNewLineSkipsPoint(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcde", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0},
-		})),
-		NewTestFeature("adbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abcde", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
+		NewTestFeature("adbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -818,7 +819,7 @@ func TestDedupNewLineSkipsPoint(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcde")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	o1Next := o1.Arc.Next
@@ -829,7 +830,7 @@ func TestDedupNewLineSkipsPoint(t *testing.T) {
 	is.Nil(o1Next.Next.Next)
 
 	o2 := GetFeature(topo, "adbe")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 0)
 	is.Equal(o2.Arc.End, 1)
 	o2Next := o2.Arc.Next
@@ -845,12 +846,12 @@ func TestDedupNewLineSkipsPointReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("edcba", geojson.NewLineStringGeometry([][]float64{
-			{4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("adbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("edcba", orb.LineString{
+			orb.Point{4, 0}, orb.Point{3, 0}, orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("adbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -859,7 +860,7 @@ func TestDedupNewLineSkipsPointReversed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "edcba")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	o1Next := o1.Arc.Next
@@ -870,7 +871,7 @@ func TestDedupNewLineSkipsPointReversed(t *testing.T) {
 	is.Nil(o1Next.Next.Next)
 
 	o2 := GetFeature(topo, "adbe")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 4)
 	is.Equal(o2.Arc.End, 3)
 	o2Next := o2.Arc.Next
@@ -886,9 +887,9 @@ func TestDedupSelfIntersectsMiddle(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {1, 0}, {4, 0},
-		})),
+		NewTestFeature("abcdbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -897,7 +898,7 @@ func TestDedupSelfIntersectsMiddle(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcdbe")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 5)
 	is.Nil(o1.Arc.Next)
@@ -908,9 +909,9 @@ func TestDedupSelfIntersectsStart(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abacd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abacd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -919,7 +920,7 @@ func TestDedupSelfIntersectsStart(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abacd")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Equal(o1.Arc.Next.Start, 2)
@@ -932,9 +933,9 @@ func TestDedupSelfIntersectsEnd(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {4, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abcdbd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{4, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -943,7 +944,7 @@ func TestDedupSelfIntersectsEnd(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcdbd")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 2)
 	is.Equal(o1.Arc.Next.Start, 2)
@@ -956,12 +957,12 @@ func TestDedupSelfIntersectsShares(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {1, 0}, {4, 0},
-		})),
-		NewTestFeature("fbg", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 0}, {2, 1},
-		})),
+		NewTestFeature("abcdbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{4, 0},
+		}),
+		NewTestFeature("fbg", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -970,7 +971,7 @@ func TestDedupSelfIntersectsShares(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcdbe")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 1)
 	o1Next := o1.Arc.Next
@@ -981,7 +982,7 @@ func TestDedupSelfIntersectsShares(t *testing.T) {
 	is.Nil(o1Next.Next.Next)
 
 	o2 := GetFeature(topo, "fbg")
-	is.Equal(o2.Type, geojson.GeometryLineString)
+	is.Equal(o2.Type, geojson.TypeLineString)
 	is.Equal(o2.Arc.Start, 6)
 	is.Equal(o2.Arc.End, 7)
 	is.Equal(o2.Arc.Next.Start, 7)
@@ -994,9 +995,9 @@ func TestDedupLineClosed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		})),
+		NewTestFeature("abca", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1005,7 +1006,7 @@ func TestDedupLineClosed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryLineString)
+	is.Equal(o1.Type, geojson.TypeLineString)
 	is.Equal(o1.Arc.Start, 0)
 	is.Equal(o1.Arc.End, 3)
 	is.Nil(o1.Arc.Next)
@@ -1016,11 +1017,11 @@ func TestDedupRingClosed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1029,7 +1030,7 @@ func TestDedupRingClosed(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
@@ -1041,16 +1042,16 @@ func TestDedupDuplicateRingsShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("abca2", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		}),
+		NewTestFeature("abca2", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1059,14 +1060,14 @@ func TestDedupDuplicateRingsShare(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "abca2")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -1078,16 +1079,16 @@ func TestDedupDuplicateRingsReversedShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("acba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0, 1}, {1, 0}, {0, 0},
+		}),
+		NewTestFeature("acba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1096,14 +1097,14 @@ func TestDedupDuplicateRingsReversedShare(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "acba")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 3)
 	is.Equal(o2.Arcs[0].End, 0)
@@ -1115,16 +1116,16 @@ func TestDedupCoincidentRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bcab", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {0, 1}, {0, 0}, {1, 0},
+		}),
+		NewTestFeature("bcab", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1133,14 +1134,14 @@ func TestDedupCoincidentRings(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "bcab")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 0)
 	is.Equal(o2.Arcs[0].End, 3)
@@ -1152,16 +1153,16 @@ func TestDedupCoincidentRings2(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bacb", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {0, 0}, {0, 1}, {1, 0},
+		}),
+		NewTestFeature("bacb", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{0, 0}, orb.Point{0, 1}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1170,14 +1171,14 @@ func TestDedupCoincidentRings2(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "bacb")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 3)
 	is.Equal(o2.Arcs[0].End, 0)
@@ -1189,21 +1190,21 @@ func TestDedupCoincidentRings3(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcda", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0},
+		NewTestFeature("abcda", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{1, 1}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("efae", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, -1}, {1, -1}, {0, 0}, {0, -1},
+		}),
+		NewTestFeature("efae", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, -1}, orb.Point{1, -1}, orb.Point{0, 0}, orb.Point{0, -1},
 			},
-		})),
-		NewTestFeature("ghcg", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 2}, {1, 2}, {1, 1}, {0, 2},
+		}),
+		NewTestFeature("ghcg", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 2}, orb.Point{1, 2}, orb.Point{1, 1}, orb.Point{0, 2},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1212,7 +1213,7 @@ func TestDedupCoincidentRings3(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcda")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 2)
@@ -1221,14 +1222,14 @@ func TestDedupCoincidentRings3(t *testing.T) {
 	is.Nil(o1.Arcs[0].Next.Next)
 
 	o2 := GetFeature(topo, "efae")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 5)
 	is.Equal(o2.Arcs[0].End, 8)
 	is.Nil(o2.Arcs[0].Next)
 
 	o3 := GetFeature(topo, "ghcg")
-	is.Equal(o3.Type, geojson.GeometryPolygon)
+	is.Equal(o3.Type, geojson.TypePolygon)
 	is.Equal(len(o3.Arcs), 1)
 	is.Equal(o3.Arcs[0].Start, 9)
 	is.Equal(o3.Arcs[0].End, 12)
@@ -1240,16 +1241,16 @@ func TestDedupNoCutsButRotated(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("dbed", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{2, 1}, {1, 0}, {2, 2}, {2, 1},
+		}),
+		NewTestFeature("dbed", orb.Polygon{
+			orb.Ring{
+				orb.Point{2, 1}, orb.Point{1, 0}, orb.Point{2, 2}, orb.Point{2, 1},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1258,14 +1259,14 @@ func TestDedupNoCutsButRotated(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abca")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 3)
 	is.Nil(o1.Arcs[0].Next)
 
 	o2 := GetFeature(topo, "dbed")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 4)
 	is.Equal(o2.Arcs[0].End, 7)
@@ -1284,16 +1285,16 @@ func TestDedupOverlapping(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcda", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0}, // rotated to BCDAB, cut BC-CDAB
+		NewTestFeature("abcda", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{1, 1}, orb.Point{0, 1}, orb.Point{0, 0}, // rotated to BCDAB, cut BC-CDAB
 			},
-		})),
-		NewTestFeature("befcb", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {2, 1}, {1, 1}, {1, 0},
+		}),
+		NewTestFeature("befcb", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{2, 1}, orb.Point{1, 1}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -1302,7 +1303,7 @@ func TestDedupOverlapping(t *testing.T) {
 	topo.dedup()
 
 	o1 := GetFeature(topo, "abcda")
-	is.Equal(o1.Type, geojson.GeometryPolygon)
+	is.Equal(o1.Type, geojson.TypePolygon)
 	is.Equal(len(o1.Arcs), 1)
 	is.Equal(o1.Arcs[0].Start, 0)
 	is.Equal(o1.Arcs[0].End, 1)
@@ -1311,7 +1312,7 @@ func TestDedupOverlapping(t *testing.T) {
 	is.Nil(o1.Arcs[0].Next.Next)
 
 	o2 := GetFeature(topo, "befcb")
-	is.Equal(o2.Type, geojson.GeometryPolygon)
+	is.Equal(o2.Type, geojson.TypePolygon)
 	is.Equal(len(o2.Arcs), 1)
 	is.Equal(o2.Arcs[0].Start, 5)
 	is.Equal(o2.Arcs[0].End, 8)
diff --git a/doc.go b/doc.go
index 5aa85ae..1a064a3 100644
--- a/doc.go
+++ b/doc.go
@@ -5,5 +5,5 @@
 // https://github.com/mbostock/topojson-specification
 //
 // Uses the GeoJSON implementation of paulmach:
-// https://github.com/paulmach/go.geojson
+// https://github.com/paulmach/orb/geojson
 package topojson
diff --git a/extract.go b/extract.go
index b76a6b1..757fe6d 100644
--- a/extract.go
+++ b/extract.go
@@ -3,7 +3,8 @@ package topojson
 import (
 	"fmt"
 
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
 func (t *Topology) extract() {
@@ -22,69 +23,78 @@ func (t *Topology) extract() {
 
 func (t *Topology) extractFeature(f *geojson.Feature) *topologyObject {
 	g := f.Geometry
-	o := t.extractGeometry(g)
+	o := t.extractGeometry(geojson.NewGeometry(g))
 
-	idProp := "id"
-	if t.opts != nil && t.opts.IDProperty != "" {
-		idProp = t.opts.IDProperty
-	}
+	// TODO
+	// idProp := "id"
+	// if t.opts != nil && t.opts.IDProperty != "" {
+	// 	idProp = t.opts.IDProperty
+	// }
 
-	id, err := f.PropertyString(idProp)
-	if err == nil {
-		o.ID = id
+	if f.ID != nil {
+		o.ID = fmt.Sprint(f.ID)
 	}
-
 	o.Properties = f.Properties
-	o.BoundingBox = f.BoundingBox
-
+	o.BoundingBox = f.BBox
 	return o
 }
 
 func (t *Topology) extractGeometry(g *geojson.Geometry) *topologyObject {
 	o := &topologyObject{
-		Type:        g.Type,
-		BoundingBox: g.BoundingBox,
+		Type: g.Type,
 	}
 
+	// TODO
+	// if g.Coordinates != nil {
+	// 	o.BoundingBox = []float64{
+	// 		g.Coordinates.Bound().Min[0],
+	// 		g.Coordinates.Bound().Min[1],
+	// 		g.Coordinates.Bound().Max[0],
+	// 		g.Coordinates.Bound().Max[1],
+	// 	}
+	// }
+
 	switch g.Type {
-	case geojson.GeometryCollection:
+	default:
 		for _, geom := range g.Geometries {
 			o.Geometries = append(o.Geometries, t.extractGeometry(geom))
 		}
-	case geojson.GeometryLineString:
-		o.Arc = t.extractLine(g.LineString)
-	case geojson.GeometryMultiLineString:
-		o.Arcs = make([]*arc, len(g.MultiLineString))
-		for i, l := range g.MultiLineString {
+	case geojson.TypeLineString:
+		o.Arc = t.extractLine(g.Coordinates.(orb.LineString))
+	case geojson.TypeMultiLineString:
+		o.Arcs = make([]*arc, len(g.Coordinates.(orb.MultiLineString)))
+		for i, l := range g.Coordinates.(orb.MultiLineString) {
 			o.Arcs[i] = t.extractLine(l)
 		}
-	case geojson.GeometryPolygon:
-		o.Arcs = make([]*arc, len(g.Polygon))
-		for i, r := range g.Polygon {
+	case geojson.TypePolygon:
+		o.Arcs = make([]*arc, len(g.Coordinates.(orb.Polygon)))
+		for i, r := range g.Coordinates.(orb.Polygon) {
 			o.Arcs[i] = t.extractRing(r)
 		}
-	case geojson.GeometryMultiPolygon:
-		o.MultiArcs = make([][]*arc, len(g.MultiPolygon))
-		for i, p := range g.MultiPolygon {
+	case geojson.TypeMultiPolygon:
+		o.MultiArcs = make([][]*arc, len(g.Coordinates.(orb.MultiPolygon)))
+		for i, p := range g.Coordinates.(orb.MultiPolygon) {
 			arcs := make([]*arc, len(p))
 			for j, r := range p {
 				arcs[j] = t.extractRing(r)
 			}
 			o.MultiArcs[i] = arcs
 		}
-	case geojson.GeometryPoint:
-		o.Point = g.Point
-	case geojson.GeometryMultiPoint:
-		o.MultiPoint = g.MultiPoint
+	case geojson.TypePoint:
+		o.Point = []float64{g.Coordinates.(orb.Point)[0], g.Coordinates.(orb.Point)[1]}
+	case geojson.TypeMultiPoint:
+		for _, v := range g.Coordinates.(orb.MultiPoint) {
+			o.MultiPoint = append(o.MultiPoint, []float64{v[0], v[1]})
+		}
 	}
 
 	return o
 }
 
-func (t *Topology) extractLine(line [][]float64) *arc {
+func (t *Topology) extractLine(line orb.LineString) *arc {
 	n := len(line)
 	for i := 0; i < n; i++ {
-		t.coordinates = append(t.coordinates, line[i])
+		t.coordinates = append(t.coordinates, []float64{line[i][0], line[i][1]})
 	}
 
 	index := len(t.coordinates) - 1
@@ -94,10 +104,10 @@ func (t *Topology) extractLine(line [][]float64) *arc {
 	return arc
 }
 
-func (t *Topology) extractRing(ring [][]float64) *arc {
+func (t *Topology) extractRing(ring orb.Ring) *arc {
 	n := len(ring)
 	for i := 0; i < n; i++ {
-		t.coordinates = append(t.coordinates, ring[i])
+		t.coordinates = append(t.coordinates, []float64{ring[i][0], ring[i][1]})
 	}
 
 	index := len(t.coordinates) - 1
diff --git a/extract_test.go b/extract_test.go
index 7d02a0e..d350fd0 100644
--- a/extract_test.go
+++ b/extract_test.go
@@ -5,7 +5,8 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
 // See https://github.com/mbostock/topojson/blob/master/test/topology/extract-test.js
@@ -15,12 +16,12 @@ func TestCopiesCoordinates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("bar", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("bar", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	expected := [][]float64{
@@ -41,9 +42,9 @@ func TestClosingCoordinates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
 	}
 
 	expected := [][]float64{
@@ -63,23 +64,23 @@ func TestLineSlices(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("bar", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("bar", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
 	topo.extract()
 
 	foo := GetFeature(topo, "foo")
-	is.Equal(foo.Type, geojson.GeometryLineString)
+	is.Equal(foo.Type, geojson.TypeLineString)
 	is.True(reflect.DeepEqual(foo.Arc, &arc{Start: 0, End: 2}))
 
 	bar := GetFeature(topo, "bar")
-	is.Equal(bar.Type, geojson.GeometryLineString)
+	is.Equal(bar.Type, geojson.TypeLineString)
 	is.True(reflect.DeepEqual(bar.Arc, &arc{Start: 3, End: 5}))
 }
 
@@ -88,17 +89,19 @@ func TestExtractRingsOrder(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("line", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("multiline", geojson.NewMultiLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("polygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("line", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("multiline", orb.MultiLineString{
+			orb.LineString{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
 			},
-		})),
+		}),
+		NewTestFeature("polygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+			},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -118,23 +121,21 @@ func TestExtractNested(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewCollectionGeometry(geojson.NewCollectionGeometry(geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {0, 1},
-		})))),
+		NewTestFeature("foo", orb.Collection{
+			orb.LineString{
+				orb.Point{0, 0}, orb.Point{0, 1},
+			},
+		}),
 	}
 
 	topo := &Topology{input: in}
 	topo.extract()
 
 	foo := GetFeature(topo, "foo")
-	is.Equal(foo.Type, geojson.GeometryCollection)
+	is.Equal(foo.Type, "GeometryCollection")
 
 	geometries := foo.Geometries
 	is.Equal(len(geometries), 1)
-	is.Equal(geometries[0].Type, geojson.GeometryCollection)
-
-	geometries = foo.Geometries[0].Geometries
-	is.Equal(len(geometries), 1)
-	is.Equal(geometries[0].Type, geojson.GeometryLineString)
+	is.Equal(geometries[0].Type, geojson.TypeLineString)
 	is.True(reflect.DeepEqual(geometries[0].Arc, &arc{Start: 0, End: 1}))
 }
diff --git a/filter.go b/filter.go
index 3627de2..8347a74 100644
--- a/filter.go
+++ b/filter.go
@@ -1,7 +1,7 @@
 package topojson
 
 import (
-	geojson "github.com/paulmach/go.geojson"
+	geojson "github.com/paulmach/orb/geojson"
 )
 
 // Filter topology into a new topology that only contains features with the given IDs
@@ -50,23 +50,23 @@ func remapGeometry(arcMap map[int]int, ids []string, g *Geometry) *Geometry {
 	}
 
 	switch g.Type {
-	case geojson.GeometryPoint:
+	case geojson.TypePoint:
 		geom.Point = g.Point
-	case geojson.GeometryMultiPoint:
+	case geojson.TypeMultiPoint:
 		geom.MultiPoint = g.MultiPoint
-	case geojson.GeometryLineString:
+	case geojson.TypeLineString:
 		geom.LineString = remapLineString(arcMap, g.LineString)
-	case geojson.GeometryMultiLineString:
+	case geojson.TypeMultiLineString:
 		geom.MultiLineString = remapMultiLineString(arcMap, g.MultiLineString)
-	case geojson.GeometryPolygon:
+	case geojson.TypePolygon:
 		geom.Polygon = remapMultiLineString(arcMap, g.Polygon)
-	case geojson.GeometryMultiPolygon:
+	case geojson.TypeMultiPolygon:
 		polygons := make([][][]int, len(g.MultiPolygon))
 		for i, poly := range g.MultiPolygon {
 			polygons[i] = remapMultiLineString(arcMap, poly)
 		}
 		geom.MultiPolygon = polygons
-	case geojson.GeometryCollection:
+	default:
 		geometries := make([]*Geometry, 0)
 		for _, geometry := range g.Geometries {
 			out := remapGeometry(arcMap, ids, geometry)
diff --git a/filter_test.go b/filter_test.go
index 239e6e2..0c04ee7 100644
--- a/filter_test.go
+++ b/filter_test.go
@@ -4,22 +4,23 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	geojson "github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb"
+	geojson "github.com/paulmach/orb/geojson"
 )
 
 func TestFilter(t *testing.T) {
 	is := is.New(t)
 
 	fc := geojson.NewFeatureCollection()
-	fc.AddFeature(NewTestFeature("one", geojson.NewLineStringGeometry([][]float64{
-		{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0},
-	})))
-	fc.AddFeature(NewTestFeature("two", geojson.NewLineStringGeometry([][]float64{
-		{1, 0}, {2, 0}, {2, 1}, {1, 1}, {1, 0},
-	})))
-	fc.AddFeature(NewTestFeature("three", geojson.NewLineStringGeometry([][]float64{
-		{1, 1}, {2, 1}, {2, 2}, {1, 2}, {1, 1},
-	})))
+	fc.Append(NewTestFeature("one", orb.LineString{
+		orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{1, 1}, orb.Point{0, 1}, orb.Point{0, 0},
+	}))
+	fc.Append(NewTestFeature("two", orb.LineString{
+		orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{2, 1}, orb.Point{1, 1}, orb.Point{1, 0},
+	}))
+	fc.Append(NewTestFeature("three", orb.LineString{
+		orb.Point{1, 1}, orb.Point{2, 1}, orb.Point{2, 2}, orb.Point{1, 2}, orb.Point{1, 1},
+	}))
 
 	topo := NewTopology(fc, nil)
 	is.NotNil(topo)
@@ -33,7 +34,7 @@ func TestFilter(t *testing.T) {
 	al2 := len(topo2.Arcs)
 	is.True(al > al2) // Arc has been eliminated
 
-	expected := map[string][][]float64{
+	expected := map[string][]orb.Point{
 		"one": {{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0}},
 		"two": {{1, 0}, {2, 0}, {2, 1}, {1, 1}, {1, 0}},
 	}
@@ -44,6 +45,6 @@ func TestFilter(t *testing.T) {
 	for _, feat := range fc2.Features {
 		exp, ok := expected[feat.ID.(string)]
 		is.True(ok)
-		is.Equal(feat.Geometry.LineString, exp)
+		is.Equal(feat.Geometry, exp)
 	}
 }
diff --git a/geojson.go b/geojson.go
index b3a08d6..5686b79 100644
--- a/geojson.go
+++ b/geojson.go
@@ -1,7 +1,8 @@
 package topojson
 
 import (
-	geojson "github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb"
+	geojson "github.com/paulmach/orb/geojson"
 )
 
 func (t *Topology) ToGeoJSON() *geojson.FeatureCollection {
@@ -9,57 +10,53 @@ func (t *Topology) ToGeoJSON() *geojson.FeatureCollection {
 
 	for _, obj := range t.Objects {
 		switch obj.Type {
-		case geojson.GeometryCollection:
+		case "GeometryCollection":
 			for _, geometry := range obj.Geometries {
 				feat := geojson.NewFeature(t.toGeometry(geometry))
 				feat.ID = geometry.ID
 				feat.Properties = geometry.Properties
-				feat.BoundingBox = geometry.BoundingBox
-				fc.AddFeature(feat)
+				feat.BBox = geometry.BoundingBox
+				fc.Append(feat)
 			}
 		default:
 			feat := geojson.NewFeature(t.toGeometry(obj))
 			feat.ID = obj.ID
 			feat.Properties = obj.Properties
-			feat.BoundingBox = obj.BoundingBox
-			fc.AddFeature(feat)
+			feat.BBox = obj.BoundingBox
+			fc.Append(feat)
 		}
 	}
 
 	return fc
 }
 
-func (t *Topology) toGeometry(g *Geometry) *geojson.Geometry {
+func (t *Topology) toGeometry(g *Geometry) orb.Geometry {
 	switch g.Type {
-	case geojson.GeometryPoint:
-		return geojson.NewPointGeometry(t.packPoint(g.Point))
-	case geojson.GeometryMultiPoint:
-		return geojson.NewMultiPointGeometry(t.packPoints(g.MultiPoint)...)
-	case geojson.GeometryLineString:
-		return geojson.NewLineStringGeometry(t.packLinestring(g.LineString))
-	case geojson.GeometryMultiLineString:
-		return geojson.NewMultiLineStringGeometry(t.packMultiLinestring(g.MultiLineString)...)
-	case geojson.GeometryPolygon:
-		return geojson.NewPolygonGeometry(t.packMultiLinestring(g.Polygon))
-	case geojson.GeometryMultiPolygon:
-		polygons := make([][][][]float64, len(g.MultiPolygon))
-		for i, poly := range g.MultiPolygon {
-			polygons[i] = t.packMultiLinestring(poly)
-		}
-		return geojson.NewMultiPolygonGeometry(polygons...)
-	case geojson.GeometryCollection:
-		geometries := make([]*geojson.Geometry, len(g.Geometries))
+	case geojson.TypePoint:
+		return t.packPoint(g.Point)
+	case geojson.TypeMultiPoint:
+		return t.packPoints(g.MultiPoint)
+	case geojson.TypeLineString:
+		return t.packLinestring(g.LineString)
+	case geojson.TypeMultiLineString:
+		return t.packMultiLinestring(g.MultiLineString)
+	case geojson.TypePolygon:
+		return t.packPolygon(g.Polygon)
+	case geojson.TypeMultiPolygon:
+		return t.packMultiPolygon(g.MultiPolygon)
+	default:
+		geometries := make([]orb.Geometry, len(g.Geometries))
 		for i, geometry := range g.Geometries {
 			geometries[i] = t.toGeometry(geometry)
 		}
-		return geojson.NewCollectionGeometry(geometries...)
+		return orb.Collection(geometries)
 	}
 	return nil
 }
 
-func (t *Topology) packPoint(in []float64) []float64 {
+func (t *Topology) packPoint(in []float64) orb.Geometry {
 	if t.Transform == nil {
-		return in
+		return orb.Point{in[0], in[1]}
 	}
 
 	out := make([]float64, len(in))
@@ -70,19 +67,19 @@ func (t *Topology) packPoint(in []float64) []float64 {
 		}
 	}
 
-	return out
+	return orb.Point{out[0], out[1]}
 }
 
-func (t *Topology) packPoints(in [][]float64) [][]float64 {
-	out := make([][]float64, len(in))
+func (t *Topology) packPoints(in [][]float64) orb.Geometry {
+	out := make(orb.Collection, len(in))
 	for i, p := range in {
 		out[i] = t.packPoint(p)
 	}
 	return out
 }
 
-func (t *Topology) packLinestring(ls []int) [][]float64 {
-	result := make([][]float64, 0)
+func (t *Topology) packLinestring(ls []int) orb.Geometry {
+	result := orb.LineString{}
 	for _, a := range ls {
 		reverse := false
 		if a < 0 {
@@ -112,28 +109,47 @@ func (t *Topology) packLinestring(ls []int) [][]float64 {
 
 		if reverse {
 			for j := len(newArc) - 1; j >= 0; j-- {
-				if len(result) > 0 && pointEquals(result[len(result)-1], newArc[j]) {
+				if len(result) > 0 && pointEquals([]float64{result[len(result)-1][0], result[len(result)-1][1]}, newArc[j]) {
 					continue
 				}
-				result = append(result, newArc[j])
+				result = append(result, orb.Point{newArc[j][0], newArc[j][1]})
 			}
 		} else {
 			for j := 0; j < len(newArc); j++ {
-				if len(result) > 0 && pointEquals(result[len(result)-1], newArc[j]) {
+				if len(result) > 0 && pointEquals([]float64{result[len(result)-1][0], result[len(result)-1][1]}, newArc[j]) {
 					continue
 				}
-				result = append(result, newArc[j])
+				result = append(result, orb.Point{newArc[j][0], newArc[j][1]})
 			}
 		}
 	}
+	return result
+}
+
+func (t *Topology) packMultiLinestring(ls [][]int) orb.Geometry {
+	result := make(orb.MultiLineString, len(ls))
+	for i, l := range ls {
+		result[i] = t.packLinestring(l).(orb.LineString)
+	}
+	return result
+}
 
+func (t *Topology) packPolygon(ls [][]int) orb.Geometry {
+	result := make(orb.Polygon, len(ls))
+	for i, l := range ls {
+		s := t.packLinestring(l).(orb.LineString)
+		result[i] = make(orb.Ring, len(s))
+		for j, l := range s {
+			result[i][j] = l
+		}
+	}
 	return result
 }
 
-func (t *Topology) packMultiLinestring(ls [][]int) [][][]float64 {
-	result := make([][][]float64, len(ls))
+func (t *Topology) packMultiPolygon(ls [][][]int) orb.Geometry {
+	result := make(orb.MultiPolygon, len(ls))
 	for i, l := range ls {
-		result[i] = t.packLinestring(l)
+		result[i] = t.packPolygon(l).(orb.Polygon)
 	}
 	return result
 }
diff --git a/geojson_test.go b/geojson_test.go
index 1f9adab..2f5c6c7 100644
--- a/geojson_test.go
+++ b/geojson_test.go
@@ -4,22 +4,22 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	geojson "github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	geojson "github.com/paulmach/orb/geojson"
 )
 
 func TestGeoJSON(t *testing.T) {
 	is := is.New(t)
 
-	poly := geojson.NewPolygonFeature([][][]float64{
-		{
+	poly := geojson.NewFeature(orb.Polygon{
+		orb.Ring{
 			{0, 0}, {0, 1}, {1, 1}, {1, 0}, {0, 0},
 		},
 	})
 	poly.ID = "poly"
-	poly.SetProperty("id", "poly")
 
 	fc := geojson.NewFeatureCollection()
-	fc.AddFeature(poly)
+	fc.Append(poly)
 
 	topo := NewTopology(fc, nil)
 	is.NotNil(topo)
@@ -35,12 +35,12 @@ func TestGeoJSONMultiArc(t *testing.T) {
 	is := is.New(t)
 
 	fc := geojson.NewFeatureCollection()
-	fc.AddFeature(NewTestFeature("one", geojson.NewLineStringGeometry([][]float64{
-		{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0},
-	})))
-	fc.AddFeature(NewTestFeature("two", geojson.NewLineStringGeometry([][]float64{
-		{1, 0}, {2, 0}, {2, 1}, {1, 1}, {1, 0},
-	})))
+	fc.Append(NewTestFeature("one", orb.LineString{
+		orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{1, 1}, orb.Point{0, 1}, orb.Point{0, 0},
+	}))
+	fc.Append(NewTestFeature("two", orb.LineString{
+		orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{2, 1}, orb.Point{1, 1}, orb.Point{1, 0},
+	}))
 
 	topo := NewTopology(fc, nil)
 	is.NotNil(topo)
@@ -50,14 +50,14 @@ func TestGeoJSONMultiArc(t *testing.T) {
 	fc2 := topo.ToGeoJSON()
 	is.NotNil(fc2)
 
-	expected := map[string][][]float64{
+	expected := map[string][]orb.Point{
 		"one": {{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0}},
 		"two": {{1, 0}, {2, 0}, {2, 1}, {1, 1}, {1, 0}},
 	}
 	for _, feat := range fc2.Features {
 		exp, ok := expected[feat.ID.(string)]
 		is.True(ok)
-		is.Equal(feat.Geometry.LineString, exp)
+		is.Equal(feat.Geometry, exp)
 	}
 }
 
@@ -77,10 +77,13 @@ func TestGeoJSONWithGeometryCollections(t *testing.T) {
 	for i := 0; i < len(result.Features); i++ {
 		is.Equal(result.Features[i].Type, expected.Features[i].Type)
 		is.Equal(result.Features[i].Properties, expected.Features[i].Properties)
-		is.Equal(result.Features[i].Geometry.Type, expected.Features[i].Geometry.Type)
 		// can't accurately compare floats for equality, so just check the array lengths
-		is.Equal(len(result.Features[i].Geometry.MultiPolygon), len(expected.Features[i].Geometry.MultiPolygon))
-		is.Equal(len(result.Features[i].Geometry.Polygon), len(expected.Features[i].Geometry.Polygon))
+		switch v := result.Features[i].Geometry.(type) {
+		case orb.Polygon:
+			is.Equal(len(v), len(expected.Features[i].Geometry.(orb.Polygon)))
+		case orb.MultiPolygon:
+			is.Equal(len(v), len(expected.Features[i].Geometry.(orb.MultiPolygon)))
+		}
 	}
 }
 
@@ -88,7 +91,7 @@ var sourceTopojson = `{
 	"type":"Topology",
 	"arcs":[[[10361,14391],[-79,-49],[-23,-39],[-14,-131],[-46,29],[-135,-28],[-27,29],[-66,17],[-63,-27],[-107,39],[-60,-25],[-86,13],[-103,28],[-110,-90],[-106,-58],[-54,25],[-3,37],[-67,17],[0,-35],[-100,56],[11,-46],[-76,-20],[-108,32],[-51,38],[1,48],[-85,2],[-10,36],[-44,28],[-48,-3],[-71,27],[-22,-45],[-63,14],[-18,-21],[-30,-127],[-55,33],[-26,40],[-40,-14],[-6,-53],[-61,-60],[-91,-42],[-63,19],[-155,67],[-51,-40],[-156,-31]],[[7794,14081],[21,42],[-6,99],[-19,88],[-47,1],[-22,59],[-68,41],[-47,54],[-62,43],[-39,110],[69,58],[-9,41],[-64,22],[-45,46],[-4,38],[81,229],[-9,64],[-62,45],[-46,63],[-37,22],[-17,52],[-94,-60],[-81,-67],[-63,-13],[-72,54],[-27,69],[17,24],[-60,94],[54,39],[19,70],[35,22],[-37,45],[-2,54],[-61,40],[48,42],[1,82],[66,54],[105,35],[-35,55],[15,25],[-12,75],[-97,-27],[-74,71],[-26,68],[-95,30],[-49,95],[-12,69]],[[6825,16343],[43,101],[60,12],[8,60],[-26,41],[65,78],[67,42],[56,70],[48,16],[54,84],[83,23],[54,-1],[29,-33],[111,55],[10,53],[-18,51],[58,22],[98,81],[55,-14],[69,52],[19,59],[-34,75],[-49,65],[-7,110],[-99,102],[-4,72],[-76,81],[7,49],[48,12],[73,-7],[61,57],[16,40],[71,84],[6,47],[48,13],[28,55],[36,-6],[17,27],[5,13],[-2,27],[27,7],[68,-16],[76,45],[101,-119],[143,-120],[52,-121],[45,-52],[49,-13],[29,38],[39,-45],[-18,-53],[20,-33],[48,44],[94,-38],[89,-110],[30,-51],[-17,-42],[38,-58],[11,-81],[36,-14],[10,-130],[21,-57],[-10,-75],[-52,-70],[37,-120],[73,-73],[-38,-93],[-2,-50],[31,-87],[46,-57],[41,-134],[-32,-72],[10,-62],[36,-45],[10,-79],[78,-101],[8,-57],[60,-114],[17,-58],[85,-74],[16,-44],[-27,-71],[25,-78],[-14,-35],[31,-134],[33,-49],[27,-91],[23,-124],[110,-145],[73,-52],[7,-78],[26,-62],[38,-41],[-18,-44],[42,-17],[61,5],[125,-42],[50,-46],[121,-50],[64,5],[50,-44],[86,-2],[110,-41]],[[7952,18119],[-1,94],[96,56],[65,-78],[-27,-36],[-76,-50],[-57,14]],[[5776,13129],[-23,-29],[25,-49],[-34,-53],[-14,103],[46,28]],[[7794,14081],[-36,-29],[-146,-5],[-75,-83],[3,-67],[27,-45],[-47,-25],[-79,-81],[93,-80],[-25,-41],[-2,-96],[16,-30],[-13,-77],[-48,-24],[-91,5],[-12,-43],[-107,4],[-36,-76],[-91,-101],[-14,-40],[-39,-21],[-11,-84],[34,-17],[39,-70],[81,-29],[28,-42],[-7,-79],[87,-17],[91,26],[22,-26],[18,-142],[48,-3],[79,-62],[101,24],[8,-63],[56,26],[19,-90],[41,-32],[59,-11],[46,-58],[8,-53],[53,-88],[54,-38],[-2,-64],[-71,-34],[-80,-62],[-3,-136],[-35,-63],[-47,-34],[23,-79],[50,-37],[30,-45],[63,6],[42,30],[46,-63],[-7,-67],[34,-77],[50,-33],[27,-49],[66,-56],[68,-102]],[[8280,11233],[-48,-101],[-70,-10],[-28,-66],[5,-79],[-76,-80],[4,-29],[56,-35],[-43,-97],[23,-99],[-18,-18],[9,-186],[18,-108],[44,-54],[-21,-44]],[[8135,10227],[-27,-63],[-83,-1],[-43,-64],[-73,-12],[-63,43],[2,-79],[-66,-34],[-87,-129],[-43,-38],[-154,-47],[-37,-64],[-61,-10],[-5,-82],[25,-36],[-19,-51],[-107,-41],[4,-35],[-73,-34],[-89,24],[-23,-69],[-49,50],[-31,-26],[-36,23],[-19,78],[-47,26],[-90,-33],[-34,29],[-51,-38]],[[6756,9514],[-59,9],[-16,27],[-64,-12],[-63,24],[-17,59],[-32,16],[10,45],[-37,137],[-44,39],[-8,54],[-77,33],[-35,32],[-39,80],[106,40],[14,33],[0,3],[-55,87],[-161,126],[-71,5],[-1,1],[-15,5],[-10,7],[-7,6],[-1,1],[-2,2],[0,0],[-3,4],[0,0],[-12,16],[29,46],[-42,27],[-26,99],[-142,164],[-3,36],[55,47],[131,60],[63,48],[47,14],[46,-93],[19,-91],[72,-109],[34,-74],[39,-47],[94,-54],[69,23],[37,28],[61,-32],[68,52],[-20,43],[-59,-16],[-45,33],[-67,-17],[-90,54],[-124,96],[-29,33],[-34,80],[-13,87],[-58,78],[2,27],[-39,76],[-5,65],[-70,64],[7,105],[60,99],[64,127],[25,20],[77,110],[50,33],[18,74],[-75,32],[-66,13],[-44,27],[-30,61],[-7,51],[5,150],[18,172],[-8,95],[230,99],[43,-32],[49,23],[41,59],[-70,74],[-24,52],[-10,83],[47,96],[112,66],[3,47],[45,42],[-36,25],[-33,62],[-38,33],[-22,74],[52,86],[-122,-38],[-66,-116],[-47,-30],[-69,32],[-12,71],[-43,53],[-34,8],[-16,-52],[2,-62],[-32,-25],[-18,-55],[-82,-105],[-76,-64],[-41,70],[-62,-31],[-32,70],[13,121],[-37,31],[75,35],[9,97],[29,51],[-6,39],[-43,43],[-19,-71],[-39,-28],[26,-51],[-23,-30],[-52,9],[-35,-25],[-43,7],[-185,291],[8,90],[-25,88],[-57,70],[-59,113],[-131,156],[-56,95],[-50,27],[-36,82],[48,24],[61,145],[-4,58],[23,39],[-10,134],[53,84],[40,37],[29,77],[37,53],[48,33],[54,69],[8,63],[-13,58],[53,124],[19,86],[62,74],[33,21],[70,-31],[59,46],[-63,49],[53,70],[70,9],[68,31],[47,-14],[90,-70],[12,57],[51,79],[53,-11],[41,78],[8,51],[36,47],[-25,94],[158,-17],[34,61],[89,49],[76,73],[73,86],[204,114],[26,49]],[[11875,11193],[-65,-32],[-55,15],[-39,-12],[-14,-83],[-61,-60],[48,-58],[-93,-47],[-23,15],[-28,84],[-42,2],[-38,56],[-3,78],[-30,64],[61,96],[-66,14],[-23,54],[-103,78],[-85,-161],[-38,-8],[-118,24],[-18,33],[-71,-79],[68,-8],[42,-44],[6,-45],[-88,-28],[-44,1],[-24,-74],[31,-32],[-149,-47],[-145,-4],[-8,84],[17,85],[-95,-1],[-117,23]],[[10465,11176],[0,91],[-13,67],[28,33],[2,73],[44,5],[12,11],[-3,24],[-20,70],[31,38],[18,59],[-11,76],[149,55],[29,-38],[99,-73],[73,7],[62,54],[89,-3],[174,44],[75,5],[69,-111],[89,-120],[96,-71],[77,-79],[57,-36],[36,13],[55,-51],[93,-126]],[[10354,10976],[-138,34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 	"transform": {
-	    "scale": [0.0005360715937289712, 0.00032300856994129236 ], 
+	    "scale": [0.0005360715937289712, 0.00032300856994129236 ],
 	    "translate": [-6.348383337142886, 49.91002832975399 ]
     },
   "objects": {
@@ -247,7 +250,7 @@ var targetGeojson = `{
       },
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50.67297457195532 ], [-4.679592465864599, 50.70559843751939 ], [-4.654933172553066, 50.715288694617634 ], [-4.653861029365608, 50.739837345933175 ], [-4.617944232585767, 50.75308069730077 ], [-4.562192786837954, 50.7815054514556 ], [-4.553615641338291, 50.83221779693638 ], [-4.55897635727558, 50.87582395387846 ], [-4.566481359587786, 50.886483236686516 ], [-4.565409216400328, 50.910708879432114 ], [-4.546110639026085, 50.928474350778885 ], [-4.549327068588459, 50.93913363358695 ], [-4.53324492077659, 50.9652973277522 ], [-4.526812061651842, 51.01891675036245 ], [-4.4640916851855525, 51.02053179321216 ], [-4.425494530437066, 51.013748613243386 ], [-4.375103800626543, 50.990168987637674 ], [-4.345083791377721, 50.98887695335791 ], [-4.3038062786605895, 50.99727517617638 ], [-4.263064837537188, 51.03377514457975 ], [-4.238405544225655, 51.04152735025834 ], [-4.221787324820058, 51.06478396729411 ], [-4.179437668915469, 51.050248581646755 ], [-4.1810458836966555, 51.06639901014382 ], [-4.214818394101581, 51.07512024153223 ], [-4.221787324820058, 51.08448749006053 ], [-4.2223233964137865, 51.11775737276449 ], [-4.2389416158193844, 51.133261784121665 ], [-4.212138036132936, 51.16007149542679 ], [-4.214818394101581, 51.18978828386139 ], [-4.201416604258356, 51.200770575239396 ], [-4.177829454134281, 51.19754048953998 ], [-4.135479798229693, 51.20916879805787 ], [-4.097954786668665, 51.2117528666174 ], [-4.080264424075609, 51.21821303801622 ], [-4.050780486420516, 51.20755375520816 ], [-4.028265479483899, 51.21627498659658 ], [-3.947318668830824, 51.22176613228558 ], [-3.9387415233311605, 51.22887232082429 ], [-3.9038968697387775, 51.229841346534116 ], [-3.89210329467674, 51.22370418370523 ], [-3.8545782831157123, 51.23436346651329 ], [-3.8063318396801047, 51.23274842366359 ], [-3.785425047524675, 51.24631478360112 ], [-3.7698789713065346, 51.2375935522127 ], [-3.6406857172178526, 51.223058166565345 ], [-3.601552490875638, 51.220474098005816 ], [-3.578501412345292, 51.23113338081388 ], [-3.5334713984720585, 51.230487363673994 ], [-3.484152811848993, 51.21918206372605 ], [-3.472895308380685, 51.20949180662781 ], [-3.4418031559444042, 51.20658472949834 ], [-3.4117831466955817, 51.18397412960245 ], [-3.3361970519797968, 51.18332811246257 ], [-3.275620961888423, 51.17977501819321 ], [-3.256858456107909, 51.18785023244175 ], [-3.1802002182046665, 51.199801549529575 ], [-3.1560769964868625, 51.208199772348046 ], [-3.1255209156443113, 51.210783840907574 ], [-3.076202329021246, 51.20141659237928 ], [-3.0242033844295357, 51.21304490089717 ], [-2.999544091118003, 51.23694753507282 ], [-3.021523026460891, 51.26504928065771 ], [-3.011873737773769, 51.30704039475008 ], [-2.9925751603995265, 51.32060675468762 ], [-2.9829258717124048, 51.346447440282915 ], [-2.962555151150704, 51.3823013915464 ], [-2.940040144214087, 51.398128811473526 ], [-2.913236564527639, 51.395867751483934 ], [-2.895546201934583, 51.40685004286194 ], [-2.8794640541227134, 51.43139869417748 ], [-2.8489079732801623, 51.45562433692307 ], [-2.7995893866570967, 51.48534112535768 ], [-2.7733218785643774, 51.49470837388597 ], [-2.7336525806284335, 51.49438536531603 ], [-2.700416141817237, 51.51731897378186 ], [-2.672540418943331, 51.545743727936696 ], [-2.663963273443667, 51.57319945638171 ], [-2.6425204096945083, 51.58708882488918 ], [-2.628046476663826, 51.605500313375835 ], [-2.5990986106024616, 51.617774639033605 ], [-2.5792639616344895, 51.63489409324049 ], [-2.5583571694790597, 51.66654893309474 ], [-2.497245007793957, 51.693358644399865 ], [-2.4816989315758167, 51.725659501394 ], [-2.4516789223269946, 51.73922586133153 ], [-2.4323803449527515, 51.736641792772 ], [-2.382525686735957, 51.75828336695807 ], [-2.3841339015171443, 51.77507981259502 ], [-2.425947485828004, 51.76409752121701 ], [-2.4709774997012373, 51.74439399845059 ], [-2.498317150981415, 51.72404445854429 ], [-2.5052860816998916, 51.71047809860676 ], [-2.5969543242275455, 51.678500250182566 ], [-2.6253661186951813, 51.66041177026585 ], [-2.623757903913994, 51.65395159886703 ], [-2.6548500563502744, 51.6216507418729 ], [-2.6698600609746856, 51.64684541032832 ], [-2.6580664859126486, 51.67656219876292 ], [-2.672004347349602, 51.68173033588198 ], [-2.668787917787228, 51.70724801290734 ], [-2.6789732780680784, 51.71403119287611 ], [-2.680045421255536, 51.72469047568417 ], [-2.685942208786555, 51.72856657852347 ], [-2.685406137192826, 51.731796664222884 ], [-2.6752207769119756, 51.73438073278241 ], [-2.6709322041621437, 51.73696480134194 ], [-2.6693239893809566, 51.74277895560088 ], [-2.662891130256209, 51.75408425554883 ], [-2.680581492849265, 51.76894264976613 ], [-2.6714682757558728, 51.79510634393137 ], [-2.650561483600443, 51.826115166645735 ], [-2.6355514789760317, 51.840973560863034 ], [-2.604459326539751, 51.85453992080057 ], [-2.5615735990414334, 51.86423017789881 ], [-2.5224403726992186, 51.86487619503869 ], [-2.5085025112622654, 51.885225734944996 ], 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[-2.16220026171335, 52.050606122754935 ], [-2.1182423910275743, 52.042207899936464 ], [-2.139685254776733, 52.02767251428911 ], [-2.1509427582450416, 52.006676957242924 ], [-2.1118095319028267, 52.01475217149145 ], [-2.0517695134051817, 52.00861500866257 ], [-1.9842244925953318, 52.035747728537636 ], [-1.9515241253778646, 52.037685779957286 ], [-1.9311534048161638, 52.03025658284864 ], [-1.9134630422231078, 52.04446895992605 ], [-1.8737937442871635, 52.024442428589694 ], [-1.8512787373505466, 52.008292000092624 ], [-1.8351965895386773, 52.00926102580245 ], [-1.826083372445285, 52.02928755713881 ], [-1.8346605179449487, 52.043176925646286 ], [-1.8571755248815656, 52.05222116560464 ], [-1.8689690999436026, 52.07386273979071 ], [-1.8464540930069857, 52.07935388547971 ], [-1.831980159976304, 52.07321672265083 ], [-1.80249622232121, 52.09679634825654 ], [-1.7676515687288274, 52.11262376818367 ], [-1.7547858504793323, 52.099380416816075 ], [-1.7279822707928831, 52.08839812543807 ], [-1.7306626287615279, 52.07353973122077 ], [-1.6899211876381264, 52.053190191314464 ], [-1.6947458319816873, 52.04059285708676 ], [-1.6566847488269305, 52.03219463426828 ], [-1.626664739578108, 52.03800878852723 ], [-1.6422108157962478, 52.01023005151227 ], [-1.6657979659203228, 51.997309708714624 ], [-1.6657979659203228, 51.98761945161638 ] ] ] ]
       }
     }
   ]
diff --git a/geometry.go b/geometry.go
index 02475c6..c81da91 100644
--- a/geometry.go
+++ b/geometry.go
@@ -5,12 +5,12 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb/geojson"
 )
 
 type Geometry struct {
 	ID          string                 `json:"id,omitempty"`
-	Type        geojson.GeometryType   `json:"type"`
+	Type        string                 `json:"type"`
 	Properties  map[string]interface{} `json:"properties"`
 	BoundingBox []float64              `json:"bbox,omitempty"`
 
@@ -29,7 +29,7 @@ func (g *Geometry) MarshalJSON() ([]byte, error) {
 	// defining a struct here lets us define the order of the JSON elements.
 	type geometry struct {
 		ID          string                 `json:"id,omitempty"`
-		Type        geojson.GeometryType   `json:"type"`
+		Type        string                 `json:"type"`
 		Properties  map[string]interface{} `json:"properties"`
 		BoundingBox []float64              `json:"bbox,omitempty"`
 		Coordinates interface{}            `json:"coordinates,omitempty"`
@@ -45,19 +45,19 @@ func (g *Geometry) MarshalJSON() ([]byte, error) {
 	}
 
 	switch g.Type {
-	case geojson.GeometryPoint:
+	case geojson.TypePoint:
 		geo.Coordinates = g.Point
-	case geojson.GeometryMultiPoint:
+	case geojson.TypeMultiPoint:
 		geo.Coordinates = g.MultiPoint
-	case geojson.GeometryLineString:
+	case geojson.TypeLineString:
 		geo.Arcs = g.LineString
-	case geojson.GeometryMultiLineString:
+	case geojson.TypeMultiLineString:
 		geo.Arcs = g.MultiLineString
-	case geojson.GeometryPolygon:
+	case geojson.TypePolygon:
 		geo.Arcs = g.Polygon
-	case geojson.GeometryMultiPolygon:
+	case geojson.TypeMultiPolygon:
 		geo.Arcs = g.MultiPolygon
-	case geojson.GeometryCollection:
+	default:
 		geo.Geometries = g.Geometries
 	}
 
@@ -83,7 +83,7 @@ func decodeGeometry(g *Geometry, object map[string]interface{}) error {
 	}
 
 	if s, ok := t.(string); ok {
-		g.Type = geojson.GeometryType(s)
+		g.Type = string(s)
 	} else {
 		return errors.New("type property not string")
 	}
@@ -98,19 +98,19 @@ func decodeGeometry(g *Geometry, object map[string]interface{}) error {
 
 	var err error
 	switch g.Type {
-	case geojson.GeometryPoint:
+	case geojson.TypePoint:
 		g.Point, err = decodePosition(object["coordinates"])
-	case geojson.GeometryMultiPoint:
+	case geojson.TypeMultiPoint:
 		g.MultiPoint, err = decodePositionSet(object["coordinates"])
-	case geojson.GeometryLineString:
+	case geojson.TypeLineString:
 		g.LineString, err = decodeArcs(object["arcs"])
-	case geojson.GeometryMultiLineString:
+	case geojson.TypeMultiLineString:
 		g.MultiLineString, err = decodeArcsSet(object["arcs"])
-	case geojson.GeometryPolygon:
+	case geojson.TypePolygon:
 		g.Polygon, err = decodeArcsSet(object["arcs"])
-	case geojson.GeometryMultiPolygon:
+	case geojson.TypeMultiPolygon:
 		g.MultiPolygon, err = decodePolygonArcs(object["arcs"])
-	case geojson.GeometryCollection:
+	default:
 		g.Geometries, err = decodeGeometries(object["geometries"])
 	}
 
diff --git a/join_test.go b/join_test.go
index 84fdd2c..dda22af 100644
--- a/join_test.go
+++ b/join_test.go
@@ -4,7 +4,8 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	"github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
 // See https://github.com/mbostock/topojson/blob/master/test/topology/join-test.js
@@ -14,12 +15,12 @@ func TestHasJunctions(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -35,12 +36,12 @@ func TestNonJunctions(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -55,12 +56,12 @@ func TestJoinDuplicate(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abc2", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abc2", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -77,12 +78,12 @@ func TestJoinReversedDuplicate(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -99,16 +100,16 @@ func TestJoinDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("abca2", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		}),
+		NewTestFeature("abca2", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -123,16 +124,16 @@ func TestJoinReversedDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("acba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {2, 0}, {1, 0}, {0, 0},
+		}),
+		NewTestFeature("acba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -147,16 +148,16 @@ func TestJoinRotatedDuplicateRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bcab", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {0, 0}, {1, 0},
+		}),
+		NewTestFeature("bcab", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -171,14 +172,14 @@ func TestJoinRingLine(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcaLine", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
-		NewTestFeature("abcaPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("abcaLine", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abcaPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -194,14 +195,14 @@ func TestJoinLineRingReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcaLine", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {0, 0},
-		})),
-		NewTestFeature("bcabPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {2, 0}, {0, 0}, {1, 0},
+		NewTestFeature("abcaLine", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("bcabPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -217,14 +218,14 @@ func TestJoinRingLineReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("bcabLine", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0}, {0, 0}, {1, 0},
-		})),
-		NewTestFeature("abcaPolygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {2, 0}, {0, 0},
+		NewTestFeature("bcabLine", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0}, orb.Point{1, 0},
+		}),
+		NewTestFeature("abcaPolygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -240,12 +241,12 @@ func TestJoinOldArcExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -263,12 +264,12 @@ func TestJoinOldArcExtendsReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -286,12 +287,12 @@ func TestJoinNewArcSharesStart(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ade", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 1}, {2, 1},
-		})),
+		NewTestFeature("ade", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 1}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -309,11 +310,11 @@ func TestJoinRingNoJunctions(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("aba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 0},
+		NewTestFeature("aba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -328,11 +329,11 @@ func TestJoinRingAANoJunctions(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("aa", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0, 0},
+		NewTestFeature("aa", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -347,11 +348,11 @@ func TestJoinRingANoJunctions(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("a", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0},
+		NewTestFeature("a", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -366,12 +367,12 @@ func TestJoinNewLineSharesEnd(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dec", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 1}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dec", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 1}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -389,12 +390,12 @@ func TestJoinNewLineExtends(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ab", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("ab", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -412,12 +413,12 @@ func TestJoinNewLineExtendsReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("ba", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {0, 0},
-		})),
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("ba", orb.LineString{
+			orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -435,12 +436,12 @@ func TestJoinNewStartsMiddle(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("bc", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("bc", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -458,12 +459,12 @@ func TestJoinNewStartsMiddleReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("bc", geojson.NewLineStringGeometry([][]float64{
-			{1, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("bc", orb.LineString{
+			orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -481,12 +482,12 @@ func TestJoinNewLineDeviates(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("abd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("abd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -505,12 +506,12 @@ func TestJoinNewLineDeviatesReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("abd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("abd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -529,12 +530,12 @@ func TestJoinNewLineMerges(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dbc", geojson.NewLineStringGeometry([][]float64{
-			{3, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dbc", orb.LineString{
+			orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -553,12 +554,12 @@ func TestJoinNewLineMergesReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("cba", geojson.NewLineStringGeometry([][]float64{
-			{2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("dbc", geojson.NewLineStringGeometry([][]float64{
-			{3, 0}, {1, 0}, {2, 0},
-		})),
+		NewTestFeature("cba", orb.LineString{
+			orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("dbc", orb.LineString{
+			orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -577,12 +578,12 @@ func TestJoinNewLineSharesMidpoint(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abc", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0},
-		})),
-		NewTestFeature("dbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 0}, {2, 1},
-		})),
+		NewTestFeature("abc", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0},
+		}),
+		NewTestFeature("dbe", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -602,12 +603,12 @@ func TestJoinNewLineSkipsPoint(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcde", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0},
-		})),
-		NewTestFeature("adbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abcde", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
+		NewTestFeature("adbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -626,12 +627,12 @@ func TestJoinNewLineSkipsPointReversed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("edcba", geojson.NewLineStringGeometry([][]float64{
-			{4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0},
-		})),
-		NewTestFeature("adbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("edcba", orb.LineString{
+			orb.Point{4, 0}, orb.Point{3, 0}, orb.Point{2, 0}, orb.Point{1, 0}, orb.Point{0, 0},
+		}),
+		NewTestFeature("adbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -650,9 +651,9 @@ func TestJoinSelfIntersectsMiddle(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {1, 0}, {4, 0},
-		})),
+		NewTestFeature("abcdbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -669,9 +670,9 @@ func TestJoinSelfIntersectsStart(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abacd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abacd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -688,9 +689,9 @@ func TestJoinSelfIntersectsEnd(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbd", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {4, 0}, {3, 0}, {4, 0},
-		})),
+		NewTestFeature("abcdbd", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{4, 0}, orb.Point{3, 0}, orb.Point{4, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -707,12 +708,12 @@ func TestJoinSelfIntersectsShares(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abcdbe", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {2, 0}, {3, 0}, {1, 0}, {4, 0},
-		})),
-		NewTestFeature("fbg", geojson.NewLineStringGeometry([][]float64{
-			{0, 1}, {1, 0}, {2, 1},
-		})),
+		NewTestFeature("abcdbe", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{2, 0}, orb.Point{3, 0}, orb.Point{1, 0}, orb.Point{4, 0},
+		}),
+		NewTestFeature("fbg", orb.LineString{
+			orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{2, 1},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -732,9 +733,9 @@ func TestJoinLineClosed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		})),
+		NewTestFeature("abca", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -750,11 +751,11 @@ func TestJoinRingClosed(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -769,16 +770,16 @@ func TestJoinDuplicateRingsShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		}),
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -793,16 +794,16 @@ func TestJoinDuplicateRingsReversedShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("acba", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0, 1}, {1, 0}, {0, 0},
+		}),
+		NewTestFeature("acba", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0, 1}, orb.Point{1, 0}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -817,16 +818,16 @@ func TestJoinCoincidentRings(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bcab", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {0, 1}, {0, 0}, {1, 0},
+		}),
+		NewTestFeature("bcab", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -841,16 +842,16 @@ func TestJoinCoincidentRings2(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("bacb", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{1, 0}, {0, 0}, {0, 1}, {1, 0},
+		}),
+		NewTestFeature("bacb", orb.Polygon{
+			orb.Ring{
+				orb.Point{1, 0}, orb.Point{0, 0}, orb.Point{0, 1}, orb.Point{1, 0},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -865,16 +866,16 @@ func TestJoinCoincidentRingsShare(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("dbed", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{2, 1}, {1, 0}, {2, 2}, {2, 1},
+		}),
+		NewTestFeature("dbed", orb.Polygon{
+			orb.Ring{
+				orb.Point{2, 1}, orb.Point{1, 0}, orb.Point{2, 2}, orb.Point{2, 1},
 			},
-		})),
+		}),
 	}
 
 	topo := &Topology{input: in}
@@ -890,14 +891,14 @@ func TestJoinCoincidentRingLine(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("abca", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {1, 0}, {0, 1}, {0, 0},
+		NewTestFeature("abca", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
 			},
-		})),
-		NewTestFeature("dbe", geojson.NewLineStringGeometry([][]float64{
-			{2, 1}, {1, 0}, {2, 2},
-		})),
+		}),
+		NewTestFeature("dbe", orb.LineString{
+			orb.Point{2, 1}, orb.Point{1, 0}, orb.Point{2, 2},
+		}),
 	}
 
 	topo := &Topology{input: in}
diff --git a/pointfeature_test.go b/pointfeature_test.go
index 3f2ce5e..a9bee2a 100644
--- a/pointfeature_test.go
+++ b/pointfeature_test.go
@@ -2,17 +2,19 @@ package topojson
 
 import (
 	"testing"
-	"github.com/paulmach/go.geojson"
+
 	"github.com/cheekybits/is"
+	"github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
 func TestPointFeature(t *testing.T) {
 	is := is.New(t)
 
 	fc := geojson.NewFeatureCollection()
-	f := geojson.NewPointFeature([]float64{0, 0})
-	f.SetProperty("id", "point")
-	fc.AddFeature(f)
+	f := geojson.NewFeature(orb.Point{0, 0})
+	f.ID = "point"
+	fc.Append(f)
 
 	topo := NewTopology(fc, nil)
 
@@ -23,11 +25,11 @@ func TestMultiPointFeature(t *testing.T) {
 	is := is.New(t)
 
 	fc := geojson.NewFeatureCollection()
-	f := geojson.NewMultiPointFeature([]float64{0, 0}, []float64{1, 1})
-	f.SetProperty("id", "multipoint")
-	fc.AddFeature(f)
+	f := geojson.NewFeature(orb.MultiPoint{orb.Point{0, 0}, orb.Point{1, 1}})
+	f.ID = "multipoint"
+	fc.Append(f)
 
 	topo := NewTopology(fc, nil)
 
-	is.Equal([][]float64{{0, 0},{1, 1}}, topo.Objects["multipoint"].MultiPoint)
-}
\ No newline at end of file
+	is.Equal([][]float64{{0, 0}, {1, 1}}, topo.Objects["multipoint"].MultiPoint)
+}
diff --git a/postquantize.go b/postquantize.go
index 1baf112..d79e6f7 100644
--- a/postquantize.go
+++ b/postquantize.go
@@ -1,6 +1,8 @@
 package topojson
 
-import geojson "github.com/paulmach/go.geojson"
+import (
+	"github.com/paulmach/orb"
+)
 
 func (t *Topology) postQuantize() {
 	q0 := t.opts.PreQuantize
@@ -48,19 +50,28 @@ func (t *Topology) postQuantize() {
 	}
 
 	for i, arc := range t.Arcs {
-		t.Arcs[i] = q.quantizeLine(arc, true)
+		a := make(orb.LineString, len(arc))
+		for i, v := range arc {
+			a[i] = orb.Point{v[0], v[1]}
+		}
+		b := q.quantizeLine(a, true)
+		c := make([][]float64, len(b))
+		for i, v := range b {
+			c[i] = []float64{v[0], v[1]}
+		}
+		t.Arcs[i] = c
 	}
 }
 
-func (t *Topology) postQuantizeGeometry(q *quantize, g *geojson.Geometry) {
-	switch g.Type {
-	case geojson.GeometryCollection:
-		for _, geom := range g.Geometries {
+func (t *Topology) postQuantizeGeometry(q *quantize, g orb.Geometry) {
+	switch v := g.(type) {
+	default:
+		for _, geom := range g.(orb.Collection) {
 			t.postQuantizeGeometry(q, geom)
 		}
-	case geojson.GeometryPoint:
-		g.Point = q.quantizePoint(g.Point)
-	case geojson.GeometryMultiPoint:
-		g.MultiPoint = q.quantizeLine(g.MultiPoint, false)
+	case orb.Point:
+		v = q.quantizePoint(v)
+	case orb.LineString:
+		v = q.quantizeLine(v, false)
 	}
 }
diff --git a/prequantize.go b/prequantize.go
index acdbd4c..03f3f2c 100644
--- a/prequantize.go
+++ b/prequantize.go
@@ -1,6 +1,8 @@
 package topojson
 
-import geojson "github.com/paulmach/go.geojson"
+import (
+	"github.com/paulmach/orb"
+)
 
 func (t *Topology) preQuantize() {
 	if t.opts.PreQuantize == 0 {
@@ -31,31 +33,29 @@ func (t *Topology) preQuantize() {
 	q := newQuantize(-x0, -y0, kx, ky)
 
 	for _, f := range t.input {
-		t.preQuantizeGeometry(q, f.Geometry)
+		t.preQuantizeGeometry(q, &f.Geometry)
 	}
 
 	t.Transform = q.Transform
 }
 
-func (t *Topology) preQuantizeGeometry(q *quantize, g *geojson.Geometry) {
-	switch g.Type {
-	case geojson.GeometryCollection:
-		for _, geom := range g.Geometries {
-			t.preQuantizeGeometry(q, geom)
-		}
-	case geojson.GeometryPoint:
-		g.Point = q.quantizePoint(g.Point)
-	case geojson.GeometryMultiPoint:
-		g.MultiPoint = q.quantizeLine(g.MultiPoint, false)
-	case geojson.GeometryLineString:
-		g.LineString = q.quantizeLine(g.LineString, true)
-	case geojson.GeometryMultiLineString:
-		g.MultiLineString = q.quantizeMultiLine(g.MultiLineString, true)
-	case geojson.GeometryPolygon:
-		g.Polygon = q.quantizeMultiLine(g.Polygon, true)
-	case geojson.GeometryMultiPolygon:
-		for i, poly := range g.MultiPolygon {
-			g.MultiPolygon[i] = q.quantizeMultiLine(poly, true)
+func (t *Topology) preQuantizeGeometry(q *quantize, g *orb.Geometry) {
+	switch v := (*g).(type) {
+	case orb.Collection:
+		for _, g := range v {
+			t.preQuantizeGeometry(q, &g)
 		}
+	case orb.Point:
+		*g = q.quantizePoint(v)
+	case orb.MultiPoint:
+		*g = q.quantizeMultiPoint(v, false)
+	case orb.LineString:
+		*g = q.quantizeLine(v, true)
+	case orb.MultiLineString:
+		*g = q.quantizeMultiLine(v, true)
+	case orb.Polygon:
+		*g = q.quantizePolygon(v, true)
+	case orb.MultiPolygon:
+		*g = q.quantizeMultiPolygon(v, true)
 	}
 }
diff --git a/prequantize_test.go b/prequantize_test.go
index edd4bed..594f6f3 100644
--- a/prequantize_test.go
+++ b/prequantize_test.go
@@ -4,7 +4,8 @@ import (
 	"testing"
 
 	"github.com/cheekybits/is"
-	geojson "github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	geojson "github.com/paulmach/orb/geojson"
 )
 
 // Sets the quantization transform
@@ -34,13 +35,13 @@ func TestPreQuantizeConverts(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
+		}),
 	}
 
-	expected := [][]float64{
-		{0, 0}, {9999, 0}, {0, 9999}, {0, 0},
+	expected := orb.LineString{
+		orb.Point{0, 0}, orb.Point{9999, 0}, orb.Point{0, 9999}, orb.Point{0, 0},
 	}
 
 	topo := &Topology{
@@ -58,7 +59,7 @@ func TestPreQuantizeConverts(t *testing.T) {
 		Scale:     [2]float64{float64(1) / 9999, float64(1) / 9999},
 		Translate: [2]float64{0, 0},
 	})
-	is.Equal(topo.input[0].Geometry.LineString, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Observes the quantization parameter
@@ -66,12 +67,12 @@ func TestPreQuantizeObserves(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
+		}),
 	}
 
-	expected := [][]float64{
+	expected := orb.LineString{
 		{0, 0}, {9, 0}, {0, 9}, {0, 0},
 	}
 
@@ -85,8 +86,7 @@ func TestPreQuantizeObserves(t *testing.T) {
 
 	topo.bounds()
 	topo.preQuantize()
-
-	is.Equal(topo.input[0].Geometry.LineString, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Observes the bounding box
@@ -94,9 +94,9 @@ func TestPreQuantizeObservesBB(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{1, 0}, orb.Point{0, 1}, orb.Point{0, 0},
+		}),
 	}
 	topo := &Topology{
 		BoundingBox: []float64{-1, -1, 2, 2},
@@ -109,10 +109,10 @@ func TestPreQuantizeObservesBB(t *testing.T) {
 
 	topo.preQuantize()
 
-	expected := [][]float64{
+	expected := orb.LineString{
 		{3, 3}, {6, 3}, {3, 6}, {3, 3},
 	}
-	is.Equal(topo.input[0].Geometry.LineString, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Applies to points as well as arcs
@@ -120,10 +120,9 @@ func TestPreQuantizeAppliesToPoints(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewMultiPointGeometry([][]float64{
+		NewTestFeature("foo", orb.MultiPoint{
 			{0, 0}, {1, 0}, {0, 1}, {0, 0},
-		}...)),
-	}
+		})}
 	topo := &Topology{
 		input: in,
 		opts: &TopologyOptions{
@@ -135,11 +134,10 @@ func TestPreQuantizeAppliesToPoints(t *testing.T) {
 	topo.bounds()
 	topo.preQuantize()
 
-	expected := [][]float64{
+	expected := orb.MultiPoint{
 		{0, 0}, {9999, 0}, {0, 9999}, {0, 0},
 	}
-
-	is.Equal(topo.input[0].Geometry.MultiPoint, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Skips coincident points in lines
@@ -147,9 +145,9 @@ func TestPreQuantizeSkipsCoincidencesInLines(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{0, 0}, {0.9, 0.9}, {1.1, 1.1}, {2, 2},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{0, 0}, orb.Point{0.9, 0.9}, orb.Point{1.1, 1.1}, orb.Point{2, 2},
+		}),
 	}
 	topo := &Topology{
 		input: in,
@@ -162,11 +160,10 @@ func TestPreQuantizeSkipsCoincidencesInLines(t *testing.T) {
 	topo.bounds()
 	topo.preQuantize()
 
-	expected := [][]float64{
+	expected := orb.LineString{
 		{0, 0}, {1, 1}, {2, 2},
 	}
-
-	is.Equal(topo.input[0].Geometry.LineString, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Skips coincident points in polygons
@@ -174,11 +171,11 @@ func TestPreQuantizeSkipsCoincidencesInPolygons(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("polygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0, 0}, {0.9, 0.9}, {1.1, 1.1}, {2, 2}, {0, 0},
+		NewTestFeature("polygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0, 0}, orb.Point{0.9, 0.9}, orb.Point{1.1, 1.1}, orb.Point{2, 2}, orb.Point{0, 0},
 			},
-		})),
+		}),
 	}
 	topo := &Topology{
 		input: in,
@@ -191,13 +188,13 @@ func TestPreQuantizeSkipsCoincidencesInPolygons(t *testing.T) {
 	topo.bounds()
 	topo.preQuantize()
 
-	expected := [][][]float64{
-		{
+	expected := orb.Polygon{
+		orb.Ring{
 			{0, 0}, {1, 1}, {2, 2}, {0, 0},
 		},
 	}
 
-	is.Equal(topo.input[0].Geometry.Polygon, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Does not skip coincident points in points
@@ -205,9 +202,9 @@ func TestPreQuantizeDoesntSkipInPoints(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("multipoint", geojson.NewMultiPointGeometry([][]float64{
+		NewTestFeature("multipoint", orb.MultiPoint{
 			{0, 0}, {0.9, 0.9}, {1.1, 1.1}, {2, 2}, {0, 0},
-		}...)),
+		}),
 	}
 	topo := &Topology{
 		input: in,
@@ -220,11 +217,11 @@ func TestPreQuantizeDoesntSkipInPoints(t *testing.T) {
 	topo.bounds()
 	topo.preQuantize()
 
-	expected := [][]float64{
+	expected := orb.MultiPoint{
 		{0, 0}, {1, 1}, {1, 1}, {2, 2}, {0, 0},
 	}
 
-	is.Equal(topo.input[0].Geometry.MultiPoint, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Includes closing point in degenerate lines
@@ -232,9 +229,9 @@ func TestPreQuantizeIncludesClosingLine(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("foo", geojson.NewLineStringGeometry([][]float64{
-			{1, 1}, {1, 1}, {1, 1},
-		})),
+		NewTestFeature("foo", orb.LineString{
+			orb.Point{1, 1}, orb.Point{1, 1}, orb.Point{1, 1},
+		}),
 	}
 	topo := &Topology{
 		BoundingBox: []float64{0, 0, 2, 2},
@@ -247,11 +244,11 @@ func TestPreQuantizeIncludesClosingLine(t *testing.T) {
 
 	topo.preQuantize()
 
-	expected := [][]float64{
+	expected := []orb.Point{
 		{1, 1}, {1, 1},
 	}
 
-	is.Equal(topo.input[0].Geometry.LineString, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
 
 // Includes closing point in degenerate polygons
@@ -259,11 +256,11 @@ func TestPreQuantizeIncludesClosingPolygon(t *testing.T) {
 	is := is.New(t)
 
 	in := []*geojson.Feature{
-		NewTestFeature("polygon", geojson.NewPolygonGeometry([][][]float64{
-			{
-				{0.9, 1}, {1.1, 1}, {1.01, 1}, {0.9, 1},
+		NewTestFeature("polygon", orb.Polygon{
+			orb.Ring{
+				orb.Point{0.9, 1}, orb.Point{1.1, 1}, orb.Point{1.01, 1}, orb.Point{0.9, 1},
 			},
-		})),
+		}),
 	}
 	topo := &Topology{
 		BoundingBox: []float64{0, 0, 2, 2},
@@ -276,11 +273,11 @@ func TestPreQuantizeIncludesClosingPolygon(t *testing.T) {
 
 	topo.preQuantize()
 
-	expected := [][][]float64{
-		{
-			{1, 1}, {1, 1}, {1, 1}, {1, 1},
+	expected := orb.Polygon{
+		orb.Ring{
+			{1, 1}, {1, 1},
 		},
 	}
 
-	is.Equal(topo.input[0].Geometry.Polygon, expected)
+	is.Equal(topo.input[0].Geometry, expected)
 }
diff --git a/quantize.go b/quantize.go
index 66a671f..2d6739e 100644
--- a/quantize.go
+++ b/quantize.go
@@ -1,6 +1,10 @@
 package topojson
 
-import "math"
+import (
+	"math"
+
+	"github.com/paulmach/orb"
+)
 
 type quantize struct {
 	Transform *Transform
@@ -22,22 +26,62 @@ func newQuantize(dx, dy, kx, ky float64) *quantize {
 	}
 }
 
-func (q *quantize) quantizePoint(p []float64) []float64 {
+func (q *quantize) quantizePoint(p orb.Point) orb.Point {
 	x := round((p[0] + q.dx) * q.kx)
 	y := round((p[1] + q.dy) * q.ky)
-	return []float64{x, y}
+	return orb.Point{x, y}
+}
+
+func (q *quantize) quantizeMultiPoint(in orb.MultiPoint, skipEqual bool) orb.MultiPoint {
+	out := orb.MultiPoint{}
+
+	var last []float64
+
+	for _, p := range in {
+		pt := q.quantizePoint(p)
+		if !pointEquals([]float64{pt[0], pt[1]}, last) || !skipEqual {
+			out = append(out, pt)
+			last = []float64{pt[0], pt[1]}
+		}
+	}
+
+	if len(out) < 2 {
+		out = append(out, out[0])
+	}
+
+	return out
+}
+
+func (q *quantize) quantizeLine(in orb.LineString, skipEqual bool) orb.LineString {
+	out := orb.LineString{}
+
+	var last []float64
+
+	for _, p := range in {
+		pt := q.quantizePoint(p)
+		if !pointEquals([]float64{pt[0], pt[1]}, last) || !skipEqual {
+			out = append(out, pt)
+			last = []float64{pt[0], pt[1]}
+		}
+	}
+
+	if len(out) < 2 {
+		out = append(out, out[0])
+	}
+
+	return out
 }
 
-func (q *quantize) quantizeLine(in [][]float64, skipEqual bool) [][]float64 {
-	out := make([][]float64, 0, len(in))
+func (q *quantize) quantizeRing(in orb.Ring, skipEqual bool) orb.Ring {
+	out := orb.Ring{}
 
 	var last []float64
 
 	for _, p := range in {
 		pt := q.quantizePoint(p)
-		if !pointEquals(pt, last) || !skipEqual {
+		if !pointEquals([]float64{pt[0], pt[1]}, last) || !skipEqual {
 			out = append(out, pt)
-			last = pt
+			last = []float64{pt[0], pt[1]}
 		}
 	}
 
@@ -48,8 +92,8 @@ func (q *quantize) quantizeLine(in [][]float64, skipEqual bool) [][]float64 {
 	return out
 }
 
-func (q *quantize) quantizeMultiLine(in [][][]float64, skipEqual bool) [][][]float64 {
-	out := make([][][]float64, len(in))
+func (q *quantize) quantizeMultiLine(in orb.MultiLineString, skipEqual bool) orb.MultiLineString {
+	out := make(orb.MultiLineString, len(in))
 	for i, line := range in {
 		line = q.quantizeLine(line, skipEqual)
 		for len(line) < 4 {
@@ -57,7 +101,22 @@ func (q *quantize) quantizeMultiLine(in [][][]float64, skipEqual bool) [][][]flo
 		}
 		out[i] = line
 	}
+	return out
+}
+
+func (q *quantize) quantizePolygon(in orb.Polygon, skipEqual bool) orb.Polygon {
+	out := make(orb.Polygon, len(in))
+	for i, ring := range in {
+		out[i] = q.quantizeRing(ring, skipEqual)
+	}
+	return out
+}
 
+func (q *quantize) quantizeMultiPolygon(in orb.MultiPolygon, skipEqual bool) orb.MultiPolygon {
+	out := make(orb.MultiPolygon, len(in))
+	for i, ring := range in {
+		out[i] = q.quantizePolygon(ring, skipEqual)
+	}
 	return out
 }
 
diff --git a/removeempty.go b/removeempty.go
index fc35bdb..25ab80c 100644
--- a/removeempty.go
+++ b/removeempty.go
@@ -1,6 +1,8 @@
 package topojson
 
-import geojson "github.com/paulmach/go.geojson"
+import (
+	geojson "github.com/paulmach/orb/geojson"
+)
 
 func (t *Topology) removeEmpty() {
 	objs := make(map[string]*Geometry, len(t.Objects))
@@ -15,7 +17,7 @@ func (t *Topology) removeEmpty() {
 
 func (t *Topology) removeEmptyObjects(obj *Geometry) *Geometry {
 	switch obj.Type {
-	case geojson.GeometryCollection:
+	case "GeometryCollection":
 		geoms := make([]*Geometry, 0, len(obj.Geometries))
 		for _, g := range obj.Geometries {
 			geom := t.removeEmptyObjects(g)
@@ -27,11 +29,11 @@ func (t *Topology) removeEmptyObjects(obj *Geometry) *Geometry {
 			return nil
 		}
 		obj.Geometries = geoms
-	case geojson.GeometryLineString:
+	case geojson.TypeLineString:
 		if len(obj.LineString) == 0 {
 			return nil
 		}
-	case geojson.GeometryMultiLineString:
+	case geojson.TypeMultiLineString:
 		linestrings := make([][]int, 0, len(obj.MultiLineString))
 		for _, ls := range obj.MultiLineString {
 			if len(ls) > 0 {
@@ -45,17 +47,17 @@ func (t *Topology) removeEmptyObjects(obj *Geometry) *Geometry {
 		if len(linestrings) == 1 {
 			obj.LineString = linestrings[0]
 			obj.MultiLineString = nil
-			obj.Type = geojson.GeometryLineString
+			obj.Type = geojson.TypeLineString
 		} else {
 			obj.MultiLineString = linestrings
 		}
-	case geojson.GeometryPolygon:
+	case geojson.TypePolygon:
 		rings := t.removeEmptyPolygon(obj.Polygon)
 		if rings == nil {
 			return nil
 		}
 		obj.Polygon = rings
-	case geojson.GeometryMultiPolygon:
+	case geojson.TypeMultiPolygon:
 		polygons := make([][][]int, 0, len(obj.MultiPolygon))
 		for _, polygon := range obj.MultiPolygon {
 			rings := t.removeEmptyPolygon(polygon)
@@ -69,7 +71,7 @@ func (t *Topology) removeEmptyObjects(obj *Geometry) *Geometry {
 		if len(polygons) == 1 {
 			obj.Polygon = polygons[0]
 			obj.MultiPolygon = nil
-			obj.Type = geojson.GeometryPolygon
+			obj.Type = geojson.TypePolygon
 		} else {
 			obj.MultiPolygon = polygons
 		}
diff --git a/topojson_test.go b/topojson_test.go
index 2ae7b01..d097e2a 100644
--- a/topojson_test.go
+++ b/topojson_test.go
@@ -3,12 +3,13 @@ package topojson
 import (
 	"fmt"
 
-	"github.com/paulmach/go.geojson"
+	orb "github.com/paulmach/orb"
+	"github.com/paulmach/orb/geojson"
 )
 
-func NewTestFeature(id string, geom *geojson.Geometry) *geojson.Feature {
+func NewTestFeature(id string, geom orb.Geometry) *geojson.Feature {
 	feature := geojson.NewFeature(geom)
-	feature.SetProperty("id", id)
+	feature.ID = id
 	return feature
 }
 
diff --git a/topology.go b/topology.go
index 28508c7..aaa1db4 100644
--- a/topology.go
+++ b/topology.go
@@ -3,7 +3,7 @@ package topojson
 import (
 	"encoding/json"
 
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb/geojson"
 )
 
 type Topology struct {
@@ -127,7 +127,7 @@ func pointEquals(a, b []float64) bool {
 
 type topologyObject struct {
 	ID          string
-	Type        geojson.GeometryType
+	Type        string
 	Properties  map[string]interface{}
 	BoundingBox []float64
 
diff --git a/topology_test.go b/topology_test.go
index 4ea3576..ee97acf 100644
--- a/topology_test.go
+++ b/topology_test.go
@@ -3,22 +3,24 @@ package topojson
 import (
 	"testing"
 
+	"github.com/paulmach/orb"
+
 	"github.com/cheekybits/is"
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb/geojson"
 )
 
 func TestTopology(t *testing.T) {
 	is := is.New(t)
 
-	poly := geojson.NewPolygonFeature([][][]float64{
-		{
+	poly := geojson.NewFeature(orb.Polygon{
+		orb.Ring{
 			{0, 0}, {0, 1}, {1, 1}, {1, 0}, {0, 0},
 		},
 	})
-	poly.SetProperty("id", "poly")
+	poly.ID = "poly"
 
 	fc := geojson.NewFeatureCollection()
-	fc.AddFeature(poly)
+	fc.Append(poly)
 
 	topo := NewTopology(fc, nil)
 	is.NotNil(topo)
@@ -30,7 +32,7 @@ func TestTopology(t *testing.T) {
 func TestFull(t *testing.T) {
 	is := is.New(t)
 
-	in := []byte(`{"type":"FeatureCollection","features":[{"type":"Feature","properties":{"id":"road"},"geometry":{"type":"LineString","coordinates":[[4.707126617431641,50.88714360752515],[4.708242416381835,50.886683361842216],[4.708693027496338,50.886514152727386],[4.70914363861084,50.886321253586765],[4.709406495094299,50.88633140619302],[4.709567427635193,50.88636524819791],[4.709604978561401,50.88647354244835],[4.709545969963074,50.88664275171071],[4.708666205406189,50.88698116839158],[4.707368016242981,50.88743464288961]]}}]}`)
+	in := []byte(`{"type":"FeatureCollection","features":[{"type":"Feature", "id":"road", "properties":{"id":"road"},"geometry":{"type":"LineString","coordinates":[[4.707126617431641,50.88714360752515],[4.708242416381835,50.886683361842216],[4.708693027496338,50.886514152727386],[4.70914363861084,50.886321253586765],[4.709406495094299,50.88633140619302],[4.709567427635193,50.88636524819791],[4.709604978561401,50.88647354244835],[4.709545969963074,50.88664275171071],[4.708666205406189,50.88698116839158],[4.707368016242981,50.88743464288961]]}}]}`)
 	out := []byte(`{"type":"Topology","bbox":[4.707126617431641,50.886321253586765,4.709604978561401,50.88743464288961],"objects":{"road":{"id":"road","properties":{"id":"road"},"type":"LineString","arcs":[0]}},"arcs":[[[0,7385],[4502,-4133],[1818,-1520],[1818,-1732],[1060,91],[650,304],[151,973],[-238,1519],[-3549,3039],[-5238,4073]]],"transform":{"scale":[2.478608990659808e-7,1.1135006529096161e-7],"translate":[4.707126617431641,50.886321253586765]}}`)
 
 	fc, err := geojson.UnmarshalFeatureCollection(in)
@@ -52,15 +54,15 @@ func TestMultiFeatures(t *testing.T) {
 	is := is.New(t)
 
 	fc := geojson.NewFeatureCollection()
-	f1 := geojson.NewPolygonFeature([][][]float64{
+	f1 := geojson.NewFeature(orb.Polygon{
 		{{0, 0}, {1, 1}, {2, 0}, {1, -1}, {0, 0}},
 		{{0.25, 0}, {0.75, -0.25}, {0.75, 0.25}, {0.25, 0}},
 	})
-	fc.AddFeature(f1)
-	f2 := geojson.NewPolygonFeature([][][]float64{
+	fc.Append(f1)
+	f2 := geojson.NewFeature(orb.Polygon{
 		{{0, 0}, {1, 1}, {2, 0}, {1, 2}, {0, 0}},
 	})
-	fc.AddFeature(f2)
+	fc.Append(f2)
 
 	topo := NewTopology(fc, nil)
 
@@ -71,11 +73,11 @@ func TestCopyBounds(t *testing.T) {
 	is := is.New(t)
 
 	fc := geojson.NewFeatureCollection()
-	f := NewTestFeature("one", geojson.NewPolygonGeometry([][][]float64{
-		{{0, 0}, {1, 1}, {2, 0}, {1, 2}, {0, 0}},
-	}))
-	f.BoundingBox = []float64{0, 0, 2, 2}
-	fc.AddFeature(f)
+	f := NewTestFeature("one", orb.Polygon{
+		orb.Ring{{0, 0}, {1, 1}, {2, 0}, {1, 2}, {0, 0}},
+	})
+	f.BBox = []float64{0, 0, 2, 2}
+	fc.Append(f)
 
 	topo := NewTopology(fc, nil)
 	is.NotNil(topo)
diff --git a/unpackobjects.go b/unpackobjects.go
index 579e87e..1d4dfa0 100644
--- a/unpackobjects.go
+++ b/unpackobjects.go
@@ -1,7 +1,7 @@
 package topojson
 
 import (
-	"github.com/paulmach/go.geojson"
+	"github.com/paulmach/orb/geojson"
 )
 
 type arcEntry struct {
@@ -29,21 +29,21 @@ func (t *Topology) unpackObject(o *topologyObject) *Geometry {
 	}
 
 	switch o.Type {
-	case geojson.GeometryCollection:
+	default:
 		for _, geom := range o.Geometries {
 			obj.Geometries = append(obj.Geometries, t.unpackObject(geom))
 		}
-	case geojson.GeometryLineString:
+	case geojson.TypeLineString:
 		obj.LineString = t.lookupArc(o.Arc)
-	case geojson.GeometryMultiLineString:
+	case geojson.TypeMultiLineString:
 		obj.MultiLineString = t.lookupArcs(o.Arcs)
-	case geojson.GeometryPolygon:
+	case geojson.TypePolygon:
 		obj.Polygon = t.lookupArcs(o.Arcs)
-	case geojson.GeometryMultiPolygon:
+	case geojson.TypeMultiPolygon:
 		obj.MultiPolygon = t.lookupMultiArcs(o.MultiArcs)
-	case geojson.GeometryPoint:
+	case geojson.TypePoint:
 		obj.Point = o.Point
-	case geojson.GeometryMultiPoint:
+	case geojson.TypeMultiPoint:
 		obj.MultiPoint = o.MultiPoint
 	}