> And is it even possible?

Well, Catmull-Clark is related to the way that cubic NURBS work. So it would be possible to export the control polygon cage for a cubic, untrimmed NURBS surface and use that to make a Sub-D surface in some other package.

The problem is that this doesn't handle the totally general case of surfaces of different degree (this is one of the different parameters that can be a part of a NURBS surface), and much worse yet, doesn't handle the case of a surface that has trim curves on it.

You get trim curves on your surfaces if you do any type of intersections, booleans, or fillets on your models - and of course these are some of the best reasons to use NURBS.

Once you have a trimmed surface, the visible geometry is not only guided just by a control polygon cage of the surface, the trim curves on it are an additional factor. There is not any easy or natural method to convert the trim curves to a SubD structure.


> Some people say that Subd is the new Nurbs.

For character modeling certainly that is the case, but it definitely isn't the new NURBS for engineering related modeling where you need more precise control over cuts. With Sub-d you can't even cut an accurate circular hole in a surface - that's a rather fundamental operation needed for creating precise man-made or manufactured objects...

- Michael