Surface mesh to volume mesh

Question

I have a closed surface mesh generated using Meshlab from point clouds. I need to get a volume mesh for that so that it is not a hollow object. I can't figure it out. I need to get an *.stl file for printing. Can anyone help me to get a volume mesh? (I would prefer an easy solution rather than a complex algorithm).

Answer 1

Given an oriented watertight surface mesh, an oracle function can be derived that determines whether a query line segment intersects the surface (and where): shoot a ray from one end-point and use the even-odd rule (after having spatially indexed the faces of the mesh).

Volumetric meshing algorithms can then be applied using this oracle function to tessellate the interior, typically variants of Marching Cubes or Delaunay-based approaches (see 3D Surface Mesh Generation in the CGAL documentation). The initial surface will however not be exactly preserved.

To my knowledge, MeshLab supports only surface meshes, so it is unlikely to provide a ready-to-use filter for this. Volume mesher packages should however offer this functionality (e.g. TetGen).

Answer 2

The question is not perfectly clear. I try to give a different interpretation. According to your last sentence:

I need to get an *.stl file for printing

It means that you need a 3D model that is ok for being fabricated using a 3D printer, i.e. you need a watertight mesh. A watertight mesh is a mesh that define in a unambiguous way the interior of a volume and corresponds to a mesh that is closed (no boundary), 2-manifold (mainly that each edge is shared exactly by two face), and without self intersections.

MeshLab provide tools for both visualizing boundaries, non manifold and self-intersection. Correcting them is possible in many different ways (deletion of non manifoldness and hole filling or drastic remeshing).