I had to solve this problem on a past project. The solution was a custom mental ray shader as it could mathematically ensure the iris was round via projecting the iris texture along the surface taking the camera's point of view into account. Using NURBS Surfaces were helpful in providing precise UV texture coordinates to more accurately map the iris to the surface as polygon meshes can only be approximated.
Other out of box techniques are approximations at best. If you try shrink wrapping the iris to a surface you run the risk of the iris' edges poking out or not completely conforming to the eyeball. Of course, either case is highly dependent on the geometry and rigging technique. If the eyes do not deform to the extreme, then shrink wrapping may be all you need. It really all boils down to how much and in which way(s) you expect the eyeballs to deform. NURBS surfaces could be really handy for this as they provide some options you don't get with polygon meshes. Matt From: [email protected] [mailto:[email protected]] On Behalf Of Enrique Caballero Sent: Monday, November 18, 2013 1:59 AM To: [email protected] Subject: Non-spherical eye while keeping iris circular Hey everyone, Does anyone have any tips on how to rig a non spherical eye while maintaining a perfectly circular iris? I have done it in the past with starting with a spherical eye, using a lattice to deform it and then using blendshapes to counter the squashing effect on the iris. But this method is clunky and you can see discrepancies in the interpolation. Any tips would be welcome, this question has bothered me for some time. -E
