STEP File Analysis API

A FastAPI-based backend service for analyzing STEP CAD files and extracting geometric, topological, and metadata information using Open CASCADE Technology (OCCT).

Features

✅ Comprehensive STEP File Analysis

Geometric properties (volume, surface area, center of mass, bounding box)
Topology information (solids, shells, faces, edges, vertices)
Assembly structure and part metadata
Quality validation and error checking

✅ RESTful API

Full analysis endpoint
Dedicated endpoints for geometry, topology, and validation
Auto-generated API documentation (Swagger/OpenAPI)
CORS support for web integration

✅ Production Ready

Docker containerization
Health check endpoints
Comprehensive error handling
Logging and monitoring

Quick Start

Prerequisites

Docker and Docker Compose
(Optional) Python 3.10+ for local development

Using Docker (Recommended)

Build and run the container:

docker-compose up --build

The API will be available at http://localhost:8000

Check API health:

curl http://localhost:8000/health

API Documentation

Once running, visit:

Swagger UI: http://localhost:8000/docs
ReDoc: http://localhost:8000/redoc

API Endpoints

Health Check

GET /health

Returns API status and OCCT availability.

Full Analysis

POST /analyze
Content-Type: multipart/form-data

file: <STEP file>

Returns complete analysis including geometry, topology, metadata, and validation.

Example Response:

{
  "file_info": {
    "file_size_bytes": 45632,
    "original_filename": "part.step"
  },
  "geometry": {
    "volume": {
      "value": 1234.56,
      "unit": "cubic_units"
    },
    "surface_area": {
      "value": 567.89,
      "unit": "square_units"
    },
    "bounding_box": {
      "min": {"x": 0, "y": 0, "z": 0},
      "max": {"x": 100, "y": 50, "z": 25},
      "dimensions": {
        "length_x": 100,
        "length_y": 50,
        "length_z": 25
      }
    },
    "center_of_mass": {
      "x": 50.0,
      "y": 25.0,
      "z": 12.5
    }
  },
  "topology": {
    "solids": 1,
    "shells": 1,
    "faces": 6,
    "edges": 12,
    "vertices": 8
  },
  "validation": {
    "is_valid": true,
    "is_done": true,
    "issues": []
  },
  "assembly": {
    "is_assembly": false,
    "part_count": 1
  }
}

Geometry Only

POST /analyze/geometry
Content-Type: multipart/form-data

file: <STEP file>

Returns only geometric properties (volume, surface area, bounding box).

Topology Only

POST /analyze/topology
Content-Type: multipart/form-data

file: <STEP file>

Returns only topology counts.

Validation

POST /validate
Content-Type: multipart/form-data

file: <STEP file>

Returns validation results and quality metrics.

Usage Examples

Using cURL

# Full analysis
curl -X POST "http://localhost:8000/analyze" \
  -F "file=@your_file.step"

# Geometry only
curl -X POST "http://localhost:8000/analyze/geometry" \
  -F "file=@your_file.step"

# Validation
curl -X POST "http://localhost:8000/validate" \
  -F "file=@your_file.step"

Using Python

import requests

# Analyze a STEP file
with open('part.step', 'rb') as f:
    files = {'file': ('part.step', f, 'application/step')}
    response = requests.post('http://localhost:8000/analyze', files=files)
    
result = response.json()
print(f"Volume: {result['geometry']['volume']['value']}")
print(f"Faces: {result['topology']['faces']}")

Using the Test Script

python test_api.py path/to/your/file.step

Using JavaScript/TypeScript

const formData = new FormData();
formData.append('file', stepFile);

const response = await fetch('http://localhost:8000/analyze', {
  method: 'POST',
  body: formData
});

const result = await response.json();
console.log('Volume:', result.geometry.volume.value);

Development

Local Development (without Docker)

Create conda environment:

conda create -n step-api python=3.10
conda activate step-api
conda install -c conda-forge pythonocc-core=7.7.2

Install Python dependencies:

pip install -r requirements.txt

Run the application:

uvicorn app.main:app --reload --host 0.0.0.0 --port 8000

Running Tests

# Start the API
docker-compose up -d

# Run test script
python test_api.py path/to/test.step

Deployment

Docker

# Build image
docker build -t step-api:latest .

# Run container
docker run -p 8000:8000 step-api:latest

Cloud Deployment

AWS ECS/Fargate

Push image to ECR:

aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin <account>.dkr.ecr.us-east-1.amazonaws.com
docker tag step-api:latest <account>.dkr.ecr.us-east-1.amazonaws.com/step-api:latest
docker push <account>.dkr.ecr.us-east-1.amazonaws.com/step-api:latest

Create ECS task definition and service

Google Cloud Run

# Build and deploy
gcloud builds submit --tag gcr.io/PROJECT-ID/step-api
gcloud run deploy step-api --image gcr.io/PROJECT-ID/step-api --platform managed

Azure Container Instances

az container create \
  --resource-group myResourceGroup \
  --name step-api \
  --image step-api:latest \
  --dns-name-label step-api \
  --ports 8000

Kubernetes

Example deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: step-api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: step-api
  template:
    metadata:
      labels:
        app: step-api
    spec:
      containers:
      - name: step-api
        image: step-api:latest
        ports:
        - containerPort: 8000
---
apiVersion: v1
kind: Service
metadata:
  name: step-api
spec:
  selector:
    app: step-api
  ports:
  - port: 80
    targetPort: 8000
  type: LoadBalancer

Configuration

Environment Variables

PORT: Server port (default: 8000)
HOST: Server host (default: 0.0.0.0)
LOG_LEVEL: Logging level (default: INFO)

Performance Considerations

File Size: The API can handle large STEP files, but processing time increases with complexity
Concurrent Requests: FastAPI handles concurrent requests efficiently
Memory: OCCT operations can be memory-intensive for large assemblies
Scaling: Deploy multiple instances behind a load balancer for high traffic

Troubleshooting

"OCCT not available" error

Ensure pythonocc-core is properly installed:

conda install -c conda-forge pythonocc-core=7.7.2

Invalid STEP file errors

Verify file is valid STEP format (.step or .stp)
Check file isn't corrupted
Ensure file contains valid geometry

Docker build issues

Increase Docker memory allocation
Check conda channel accessibility
Verify network connectivity

Technology Stack

FastAPI: Modern, fast web framework
pythonocc-core: Python bindings for Open CASCADE
OCCT: Open CASCADE Technology for CAD processing
uvicorn: ASGI server
Docker: Containerization

License

This project uses Open CASCADE Technology which is under LGPL 2.1 license.

Contributing

Fork the repository
Create a feature branch
Make your changes
Submit a pull request

Support

For issues and questions:

Check the API documentation at /docs
Review OCCT documentation
Open an issue on GitHub

Roadmap

Support for additional CAD formats (IGES, BREP)
Async processing for large files
WebSocket support for progress updates
Cloud storage integration (S3, Azure Blob)
Caching layer for repeated analyses
Authentication and rate limiting
Batch processing endpoint

Name		Name	Last commit message	Last commit date
Latest commit History 1 Commit
ARCHITECTURE.md		ARCHITECTURE.md
DEPLOYMENT.md		DEPLOYMENT.md
DEPLOY_GOOGLE_CLOUD.md		DEPLOY_GOOGLE_CLOUD.md
DEPLOY_RAILWAY.md		DEPLOY_RAILWAY.md
DEPLOY_RENDER.md		DEPLOY_RENDER.md
Dockerfile		Dockerfile
PROJECT_STRUCTURE.md		PROJECT_STRUCTURE.md
QUICKSTART.md		QUICKSTART.md
README.md		README.md
__init__.py		__init__.py
docker-compose.yml		docker-compose.yml
environment.yml		environment.yml
generate_samples.py		generate_samples.py
main.py		main.py
requirements.txt		requirements.txt
step_processor.py		step_processor.py
test_api.py		test_api.py
test_curl.sh		test_curl.sh

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