I have decided to continue with the facial rigging as this suits my currently available time schedule better.
I started with rigging the eyes. Major sources of information and inspiration were the Mancandy rig as well as the facial rig tutorial by Paul Cageggi. I also got a lot of information from Gordon Goodwin’s rigging repository.
The rigging process itself was relatively straight forward and the used techniques quite clear. The really time consuming part was the weight painting and additionally reworking the mesh.
After I had set up the rig the deformation was horrible. Even with decent weight painting I had grotesque deformations on the eye lids. I was nearly at the point of abandoning this rig setup when I remembered ,that I had weight painted the whole head (including the eye area) for the head bone. The weight was set to 1 for this bone. This was the source of the horrible deformations I was witnessing. If the surrounding mesh is all nearly pinned with a weight of 1, you have not much control left.
So I cleared the head vertex group and started weight painting again. As I should have guessed this wasn’t a great idea either, as now the slightest weight – and be it only 0.001 – immediately started moving the vertices without damping. So the solution was to put some weight on the head vertex group which provided some initial pinning which is overcome by the influence the eye lid bones are providing. Once this was done the actual weight painting of the lids was a relatively easy thing to do.
The result was almost pleasing, almost. This ‘almost’ sent me back to reediting the mesh. Having not only a clean topology but also a clean mesh helps the deformation in extreme setups like those of the eye lids. By clean mesh I mean having the edges (without the subsurf modifier) going in a smooth fashion and not zig-zagging around wildly. The subsurf modifier hides these problems and only when starting deforming you realize something’s amiss.
I am quite satisfied with the current setup and think it will also be sufficient for the several extreme closeups of the eyes. At this time there are no corrective shape keys used, its pure bone deformation.
See here for some examples of eye-posing
I have also done a small test animation. See here two versions, one a viewport rendering where you can see rig controls and then the same animation rendered.
I will continue with the face rigging. The next part should be the areas around the eyes and the brow.