It has been quite a long time since we discussed about skinning techniques, but I still want to revise some of the points that I found interesting.
The basic idea of skinning is easy to understand: just to assign the vertices on the "skin" to corresponding bones, so the "skin" will move together with its bone. It becomes interesting when the "Candy Wrapper" artifact appears. Since the connected bones might rotate to different directions, the skin at the joint will twist because its vertices are assigned to different bones. The visual results can be improved by assigning more weights to a vertex. The non-linear method called Dual Quaternion Blending method (DQB) can also solve the problem. This method is very fast, although it might work when strange motions are involved, like wrapping around. This can be solved by breaking the transformation into phases.
There are also issues with bulging artifacts, and a "cage" method was introduced by a research to guide the muscle bulging, sliding and twisting. I found it interesting because the "cage" method was an old technique introduced for skinning, and it's surprising to see modern modifications based on historic methods.
Some research about general deformers were also discussed during classes. I was wondering why my artist friends still hate skinning so much due to massive manual operations involved in the process. Maybe the good methods are not well developed for prevalent commercial use.
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