May 26, 2008
A while back someone wrote a siggraph paper on using dual quaternions for a more advanced skinning. Unlike linear skinning, dual quarternions don’t suffer from the “shrinkage” problems and require far less corrective shape keys as a consequence.
I’ve used this in my own rig, and it seems to work great. It’s implemented in Blender, and the site has links to plugins for Maya and XNA.
May 26, 2008
So, here’s my first post: Shoulder Deformation.
This is actually a topic I’ve spent a great deal of time on. My theory for the main problem with shoulder deformation is twofold: a) people don’t realize you can’t lift your arm above your shoulder, going higher requires rotating your shoulder itself, and b) they don’t build support for twisting into their upper arm rig.
You can test both aspects of this theory yourself. Try lifting your arm above your head without moving your shoulder. And try twisting your upper arm and see what happens. The upper arm twists, it doesn’t rotate in a block. Trying to blend between the upper arm and the shoulder with weights won’t help either, a true volume-preserving twisting rig is needed.
May 26, 2008
Since I seem to have a lot of free time this summer, I’ve decided to start a rigging and animation blog. This site will mostly feature various books and tools that sound cool, but will also document some of the knowledge I’ve accumulated in my past adventures learning the black art of character rigging.
Note that I’m in no way a professional or expert on animation or rigging (though I am fairly good for an amataur at rigging, I think).
