Converting Meshes to Conforming Quad NURBS Surfaces

What We Solved?

This repository provides tools to convert triangulated and quad meshes into a union of conforming quad NURBS surfaces, which are widely used in isogeometric analysis. The resulting NURBS surfaces are stored in a format compatible with the geometry file structure of the Boundary Element Method Based Engineering Library (Bembel).

How to Use?

To run the conversion process, use the following command:

python partition.py --input mesh/david.obj --num 350 --start 340 --id 340 --output outputname.dat

Command-Line Arguments

• --input: Specifies the input mesh file. Supported formats: .obj, .vtk.
• --num: The number of eigenfunctions to compute.
• --id: Specifies which eigenfunction to use for the partitioning.
• --output: The name of the output file where the NURBS surface data will be saved.

Code Structure

The code is organized as follows:

• __init__.py: Initializes the module.
• eigens.py: Contains functions related to eigenfunction computations.
• io.py: Handles input/output operations.
• morseSmaleQuadrangulation.py: Implements the Morse-Smale complex-based quadrangulation.
• nurbs.py: Functions for creating and manipulating NURBS surfaces.
• patches_search.py: Algorithms to search and partition patches in the mesh.
• utils.py: Utility functions used throughout the code.

Acknowledgements

This project makes use of the following libraries:

• Topology ToolKit (TTK) for the Morse-Smale complex computation.
• NURBS-Python (geomdl) for NURBS interpolation.
• libigl for computing the eigenfunctions and mesh IO.

Final Remarks

• The current implementation supports input mesh formats .obj and .vtk.
• Not all eigenfunctions are suitable for obtaining a proper partition; careful selection is needed.
• Some parameters in the Morse-Smale module may need fine-tuning to achieve optimal results.

Contact

For any issues or questions, feel free to open an issue on this repository.