Can someone explain to me or point me to a resource that describes how Valve and Epic are achieving iris movement for dynamic tracking behavior? [img]/images/graemlins/ooo.gif[/img]

well I presume they are using face fx , using look at controllers in max. So they would have proper eyeballs instead of animated uv's

tons of games use the animated uvs thing, like doom3, not sure how it is done. i know you can animate uvs pretty easily, but i dont know the export process.

I would actually prefer do it that way, as it can be a pain to work with a proper eyeball ie the intersection with the eyelid for one.