Re: [Algorithms] Algo for weight assignment in skinned animation

[Jon W. <jw...@gm...>]

Bill Baxter wrote:
> Is there any standard algorithm used for automatically assigning
> reasonable bone weights to vertices in a mesh, given just the mesh and
> the skeleton?  (I.e. you have no animation data, so you can't use
>   

There is no *good* algorithm.

I've tried finding the closest bone behind the surface, with some 
favoring of bones closer to the reverse vertex normal. In this case, a 
"bone" is not just the rotation center, but an imaginary line from the 
center of the bone rotation matrix to the center of the child rotation 
matrix (and there will be multiple such lines for a single bone with 
multiple children). It is by no means great, but at least it gets the 
skin deforming. Knees, elbows and arm pits will never look good with 
automatic weights. In general, it's really no better than what you get 
when you reset a skin or Physique deformer modifier to all default 
envelopes in 3ds Max... Well, except you can make it so you never end up 
with "floating" vertices :-)

In fact, I know some artists who claim they will never look good with 
only skinning at all, that you need bulge deformers at a minimum :-)

Sincerely,

jw


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