Hi Bard,

> It goes to miss some functions to create skins with a lot
> of irregularities; and why not, commands of erosion &
> corrosion (I don't know if it's possible with NURBS).

NURBS by themselves are not very well suited for that - mostly because a NURBS surface is made up of a rectangular grid of points, so to add a little divot in one area of a NURBS surface you actually have to add in an entire row or column of control points. Polygon or sub-d methods tends to be better for adding that type of detail because they can add more polygon faces in a small localized area.

Also corrsion or weathering is often added using displacement texture mapping or rendering shaders rather than explicit modeling of the weathering itself.

If you do want to model corrosion or little bumps and stuff like that, one of the brush-based sculpting programs like ZBrush or 3D-Coat are better suited for that kind of stuff rather than trying to do it with NURBS. NURBS modeling can work well for building the kind of ideal smooth starting surface though.

- Michael