   Correction of normal vector / vertex winding of a triangulation mesh
  Hello folks,I have a triangle mesh recovered from a Delaunay triangulation.However, a lot of the face normals are not pointing in the right direction (outwards), probably due to incorrect vertex winding. I know that 3D modeling tools don't have a concept of inwards/outwards, but are there tools that can flip the normals based on some kind of global criterion? For example, that I can make all normals point away from the center of gravity of the mesh (they should just flip however and not realign completely). If possible, the winding should be corrected too so other progras calculate them correctly for themselves afterwards.I'm using 3DS Max mainly but also Blender.Regards   
  Blender has an option to reconstruct all normals inward or outward. Go into edit mode, select all and press CTRL-N (CTRL-Shift-N for inward).;  Which criterion does Blender use to find out wheres inside and wheres outside?   ;Quote:Original post by DesperadoWhich criterion does Blender use to find out wheres inside and wheres outside?Uhhm... I don't know the internal algorithm, but it works really good. Blender is open source, so just take a look at the source code.;  Well, it didn't work. Almost none of the inward pointing faces have been flipped.   