Does generateMesh create a volumetric mesh or a surface mesh?

Hi,

I am wondering if this function creates a volumetric or a surface mesh. I am guessing surface, but I cannot seem to find it anywhere for sure, and I am not really sure how to check this.

Thanks in advance!

Answer 1

[Shubham]

Hi Kassandra,

The process described above using alphaShape and triangulation is intended to create a surface mesh, not a volumetric mesh. Here's how you can confirm and understand the distinction:

Surface Mesh vs. Volumetric Mesh

• Surface Mesh: Represents only the outer boundary of a 3D object. It consists of vertices, edges, and faces (usually triangles), and is typically used for visualization, rendering, and surface analysis.
• Volumetric Mesh: Represents the entire volume of a 3D object, including its interior. It consists of elements like tetrahedra or hexahedra and is used for simulations such as finite element analysis (FEA).

Confirmation Steps

1. Examine the Output Structure:

• The triangulation object created from boundaryFacets contains only vertices and triangular faces, indicating a surface mesh.
• You can inspect the TR object in MATLAB to see that it only includes surface information:

TR.Points % Lists vertices
TR.ConnectivityList % Lists triangular faces

2. Visual Inspection:

• Visualize the mesh using MATLAB's plotting functions to confirm it's a surface:

trisurf(TR, 'FaceColor', 'cyan', 'EdgeColor', 'none');
axis equal;
camlight;
lighting gouraud;

• This visualization will show only the outer shell of the object, characteristic of a surface mesh.

3. STL File Format:

• The STL file format itself is inherently a surface representation format. It describes 3D geometries using only triangular facets without any volumetric information.

Creating a Volumetric Mesh

If you need a volumetric mesh, you would typically use software or libraries specifically designed for this purpose, such as:

• TetGen: For generating tetrahedral meshes.
• Gmsh: A 3D finite element mesh generator with built-in pre- and post-processing facilities.
• CGAL: The Computational Geometry Algorithms Library for more complex meshing tasks.

These tools take a surface mesh and fill the interior with volumetric elements, which can then be used for simulations or analyses that require volumetric data.