Hi PaQ,

> (I was thinking that every rendering engine have to
> tesselate the nurbs model :)

I guess it kind of depends on what your exact definition of tessellate is...

But the REYES / RenderMan style approach is to subdivide NURBS surfaces into smaller and smaller pieces until you get pieces that are smaller than a pixel (a "micropolygon").

So it kind of does tessellate because there is a conversion from NURBS into polygons, but on the other hand it is a different style of tessellation than the conventional kind of mesh conversion because it happens to a level of detail to where you can't see any evidence of the polygon conversion...

- Michael