This paper describes the topic of using multiple skin samples to
automatically calculate joint weights, which we talked about in class.
To do this we need examples, which are a pair of skeleton config and
a static mesh that represent the character in that skeleton config.
Then using those samples, it solves a bilinear least-squares problem
to fit the parameters. It also adds extra joints by examining rotations
of joints relative to dress pose and adding joints at halfway slerps
to handle deformations that can't be done by the existing structure.
After finding the influence sets and solving the weights, the paper
briefly describes how normals are handled.
This seems like a practical and effective way to improve skinning
for real-time environments where number of joints aren't the main
performance concern. In MMORPGs joint number is one of the biggest
bottle necks but discrete bone LODs could be used.