Hi Felix,

> Though I can understand the major difference between Sub-D and Nurbs
> I would have thought the transition between the 2 would have been made
> much easier by now.

The problem is that sub-d requires a particular kind of topology and edge flow which is usually implemented by a human using their judgement and experience on how to arrange all the elements.

It's quite difficult to replicate processes that require judgement like that since they're not like checking off a list of simple yes/no type decisions like a computer algorithm is fundamentally based off of.

Retopologizing toolsets are probably what you would need to be focusing on if you need to do this kind of conversion.

- Michael