Subdividing an STL


#1

HI I would like to subdivide a mesh coming from an STL file.
I am trying the split and mesh boolean but the mesh gets destroyed.

Please find attached the file in case something is wrong with it. I dowloaded from NASA web.

gale_crater.STL.zip (13.1 MB)

Thanks

Bruno


(Brian James) #2

Rhino doesn’t have the ability to subdivide meshes, only to reduce, repair and edit them. In this particular case you could use Drape to drape a surface over the mesh and then make a new mesh from that at a new density but it’s already pretty dense on the top.

The issue with this mesh is that the sides of the slab have polys that go above and past the edges of the polys at the top border. Make a rectangle slightly inside this border as seen from the Top view and MeshSplit will work.You’ll need to use ExtractMeshPart too to select and delete the bottom mesh after this initial split to get rid of the trouble spots.


#3

Thanks a lot…after extracting the bottom mesh how can i cover it ?


(Brian James) #4

If you mean get a closed solid mesh from the remaining top… I’d use ExtrudeCrv with the rectangle used to split the mesh so there are surfaces stretching past the mesh in the Z axis. Then use DupBorder to get a border curve from the top mesh and use it to trim the planar surfaces you just extruded. Use Cap to close the bottom of that polysurface and then Mesh to make a mesh from it. Finally Join to join the top mesh with the new side walls and flat bottom.


#5

Ok i will try . Thanks I did not know i can use those operations in mesh mode