[Bf-committers] unwrapping on subsurfed meshes

[Brecht Van Lommel]

Hey,

Giving the subsurfed uv coords as input the lscm is not the solution.
Take for example a subsurf mesh consisting of a single quad. This
will just make the uv's smaller, not fix the issue.

Tom M wrote:
>>the only way I can see to cram the problems into the texture mapping
>>instead of the modeling is to let the artist define how the texture
>>coordinates are interoplated across the face.
> 
> 
> More likely solution is have subdiv surface interpolate uv coords
> 'correctly' when subdivided.  I think the update to modos 'SDS smooth
> uv interpolation' was to address a similar issue in modo.  A quick
> search of the literature didn't have anything that jumped out at me as
> the right solution though.

The right thing to do is to subsurf the uv mesh as if it was a 3d mesh
mesh. For those who like the literature:

"Subdivision surfaces in character animation", DeRose et al.
http://www.cs.rutgers.edu/~decarlo/readings/derose98.pdf

"Subdivision for Modeling and Animation", Siggraph 2000 course notes
http://mrl.nyu.edu/publications/subdiv-course2000/

But, seams need special treament, and I haven't seen any mention of
them in the literature. One way is to fully crease them, but it's not perfect.
Lightwave 8.2 provides a bunch of options for dealing with seams, but I
don't know what these options do exactly. Personally I think it might be
good idea to 'extrapolate' the uv mesh boundary and then apply subsurf.

Brecht.