HELP: Mesh Boolean Split doesn’t work in a closed mesh, but bad mesh


Could you help me please make a Mesh Boolean Split between the mesh represented by the Moon and the other surfaces?

According to Check Objects (Rhino V.5) this moon is a closed mesh without any naked edges, but it is a bad mesh with degenerate faces, non manifold edges and duplicate faces.

It was generated by Height Field from Image and then Mesh Boolean Split to create a closed mesh (till this step it was a good and closed mesh). The following command ApplymeshUVN created this bad mesh. When I solve the listed problems I have an open mesh with naked edges and I can’t make Mesh Boolean Split neither.

The objective is to create an exploitable STL file.

You can find above the link to access the file as a Rhino V.4 (I still have some saves lefts in my V5 evaluation so I still can explore a V5 file).

Do you have any suggestions, please?




Hi Marcia,

the problems you´ve been facing with mesh boolean split are of course related to the degenerate faces, duplicates and mesh normals. It`s also related to the small size that mesh faces have, they got degenrate because of numerical tolerances. Once you´ve used ApplyMeshUVN it just distorts the mesh further at the poles of the sphere.

If you create a vertical ClippingPlane (this takes a while) and look inside the mesh, all problems are visible. I´ve tried to fix the mesh first and then boolean split worked. The file is saved as v4 file. link


Hi Clement,

I did appreciate your help, thanks a lot! It was life-saving. :wink:

I tried to make as you suggested and solve the problems with cull degenerate faces, extract non manifold edges and extract duplicate faces.

The mesh was good, but open. To close the 1500 naked edges I tried Align mesh vertices to tolerance (reduced to 75 naked edges), Match mesh edges (22 naked edges), Unify mesh normal (12 naked edges), Fill mesh holes (7 naked edges) but those last ones I can’t vanish them!

Do you recall which commands you used to rebuild the mesh or which commands do you normally use, please?


Thanks Marcia,

i´ve not used Rhino to fix the mesh because i could not turn points on, the mesh has more than 1 million polygons and Rhino prevented further edits. To fix it with 3 clicks, i´ve exported via OBJ format and used MeshMixer, its a free application.


Thanks a lot, Clement. MeshMixer sounds interesting. I will try this application.