Shifty Geezer said:
The problem with joint rotation based morphing is, that it has difficulties handling any joint with more than one rotation axis - like the hips and shoulders, which are usually the hardest to set up properly using any method. The solution is to work with poses and pose-space based deformations - but that will take a lot of blendshapes, for example ILM's Hulk had about 150 or so shapes, all sculpted individually. That's a lot of work... and they also had to do a lot of shot-dependent fixes.
Also, it wont get you proper secondary dynamics, to show jiggling flesh and wrinkling or sliding skin. The Hulk used some extra springs inside his limbs, and a cloth-like simulation to keep his skin from stretching and distorting. The illusion of muscles moving under the skin is created by differentiating between the form and the surface texture, and animating them differently. When that bicep flexes, it's moving under the skin, not with the skin.
Other solutions are to actually build up muscle masses from tubular objects and have them flex and bend and jiggle as necessary; and then, simulate the skin sliding and wrinkling effects. Weta used this for Gollum, as did Tippet Studio for Hellboy characters and most of their other shows, I assume.
So the first method is more artist-driven, but takes a lot of artist work as well. The second is more technical, and also takes a lot of time to set up and is more prone to errors.
Implementing them in realtime is probably not going to happen with this generation - pose based deformation takes a lot of extra memory for all the shapes, muscles are far too expensive to calculate, and in both cases you can't wait for hours to simulate the skin...
