Hi Paul -
I - kind of - already answered that in your other thread. I then wrote “You can’t (or not really) create a SubD object from a polysurface.”
More complete information from the help file:
The ToSubD command converts supported object types into SubD objects.
Mesh, Extrusion, Surface, Sub-surface
Polysurfaces are not eligible inputs for the
Also from the help file:
- Trims of a surface or sub-surface will be lost in the SubD.
- Sub-surfaces of a polysurface will be converted individually.
So, unless all sub-surfaces of your polysurface are untrimmed, the individual SubD objects won’t be the same as the original and thus the ToNURBS version thereof won’t be the same of that original.