[vtkusers] detecting if surface is convex

[Bryn Lloyd]

Hi,


Is there any code in VTK that would help with detecting if a closed 3d 
surface (or equivalently a connected set of tetrahedra) is convex or 
concave?

My own attempts have been to compute the dihedral angles at each edge on 
the surface. If at least one is larger than PI -> concave. This is not 
very robust though, especially for flat surfaces.


Thanks
Bryn