> > Looks pretty easy to code in user space to me. > Catmull Clark is certainly something that can be implemented, but the sort of thing that I had in mind would apparently be called an "interpolating scheme" rather than an "approximating scheme". (And Catmull-Clark is an "approximating scheme".) https://en.wikipedia.org/wiki/Subdivision_surface Interpolating schemes have the property that subdivision leaves the vertices in the mesh in place, which is a desired property when people trying to generate a surface that matches a set of control points. Wikipedia lists butterfly, modified butterfly, and Kobbelt as interpolating schemes. I found a paper on the butterfly method, but it's not as accessible as the Catmull-Clark wikipedia page. http://www.math.tau.ac.il/~niradyn/papers/butterfly.pdf Apparently the butterfly method only works for "nice" meshes, but that can probably be managed by picking a suitable set of control points from the sample.