Self Intersecting Faces on a Volumetric Mesh of a Tube

Hello, have unique xyz coordinates (x,y,z) in a 2D matrix which I am trying to use as the boundaries of a volumetric mesh of a tube. I have been able to make a triangulation using alphashape, however when I go to make the mesh it has self-intersecting faces utilizing Tetgen. I do not have the CAD model and the mesh is quite large - is there a way to fix the self intersecting faces or prevent them from happening?

shp = alphaShape(x,y,z);

[faces, vertices] = boundaryFacets(shp);

TR = triangulation(faces,vertices);

meshOutput=runTetGen(inputStruct);

Thank you,

Ruth

[pardhasaradhi]

have u solved the solution

Answer 1

[Shubham]

Hi Ruth,

Dealing with self-intersecting faces in a volumetric mesh can be challenging, especially with large datasets. Here are some strategies you can consider to address this issue:

1. Preprocessing the Data

• Clean the Input Data: Ensure that the input coordinates are free from noise and duplicates. You can use techniques like clustering to remove outliers or use a small epsilon to merge nearly identical points.
• Simplify the Geometry: If the dataset is too large, consider simplifying the geometry using techniques like point cloud decimation or mesh simplification algorithms (e.g., Quadric Error Metrics).

2. Adjusting Alpha Shape Parameters

• Tune Alpha Value: The alpha parameter in alphaShape controls the detail level of the shape. A smaller alpha value might result in fewer self-intersections as it creates a tighter fit around the data points.

alphaValue = 0.1; % Adjust this value as needed
shp = alphaShape(x, y, z, alphaValue);

3. Post-processing the Mesh

• Remove Self-intersections: Use mesh repair tools available in software like MeshLab or MATLAB functions to detect and correct self-intersections.
• Use Mesh Smoothing: Apply smoothing algorithms to reduce sharp angles or irregularities that might lead to self-intersections.

4. Debugging

• Visualize Problem Areas: Use visualization tools to identify where the self-intersections occur. This might give you insights into why they are happening and how to fix them.
• Iterative Approach: Start with a smaller subset of your data to understand the behavior of the meshing process, then gradually increase the complexity.