Originally Posted by

**GClements**
Non-smooth subdivision normally means that you treat a set of faces as being just that: faces of some polyhedron. Subdividing gives exactly the same polyhedron, just with more vertices and faces.

Smooth subdivision treats the faces as being an approximation to a smooth surface. Subdivision creates a better approximation to the surface.

Smooth subdivision is more complex because you typically want each level of subdivision to be self-contained (i.e. the subdivided geometry replaces the original geometry) while the limit of a sequence of repeated subdivisions is determined by the original geometry.

Non-smooth subdivision is simple enough that there isn't really much that needs to be written about it. It's basically a solved problem, there aren't going to be any new "algorithms" developed. It's just a matter of choosing where to subdivide, at which point the resulting vertices are known.