Dual Quaternion Skinning

Chatterbox · Post by **Chatterbox** » Thu May 08, 2008 3:44 pm

Classical skinning has the well known "elbow" problems when bending.

New techniques exist to solve this. For example, "dual quaternion skinning" http://isg.cs.tcd.ie/projects/DualQuaternions

It would be great to incorporate the work of the above authors in Ogre

They already made a plugin for maya, and all the source code is available, plus a paper. I'm not sure about the licensing.

Cheers,
Peter

Post by **tuan kuranes** » Thu May 08, 2008 4:33 pm

New techniques exist to solve this

Pose Space Deformation (PSD) does this too. A very popular opensource PSD plugin exists for maya, done by the great Micheal Comet

It solves both the elbow problem and the pose shape complexity generation problem.

WPSD would be great too, but this one seems a bit slow, even if more correct 'physically'.

Chatterbox · Post by **Chatterbox** » Thu May 08, 2008 9:40 pm

Regarding pose space deformation, in 1997 my former R&D team developed a similar albeit less advanced technique: one could assign a morph target to any n-dimensional set of angles or other linear parameters, and the system would then interpolate between those morph targets. The problems we experienced back then was (1) that we used Euler angles instead of quaternions and (2) we used linear nearest neighbor interpolation instead of the more smooth "natural neighbor" interpolation

The 3D animation software we developed was supposed to be used to create a 3D movie, but unfortunately the motion picture studio choose to invest in another movie, and after that unfortunate event, it didn't took much time before the company I was working for went defunct.

It's great that a plugin for Maya exists that does something similar! I know a couple of artists that will love that. I'm gonna read the paper in detail. Thanks!

Do you think one of these techniques might end up in Ogre?

Do you also have plans to support the new generation of video cards with unified shader architecture and geometry shaders? Lots of algoritms can now be run completely on the GPU I guess.

Post by **Praetor** » Thu May 08, 2008 11:22 pm

Yes, geometry shader support is in the works.

Post by **tuan kuranes** » Fri May 09, 2008 1:52 pm

I'm gonna read the paper in detail.

You should also read the WPSD paper, as it analyze PSD and gives hints on its implementation resutls.

If you're an Ogre user of both skeletal and pose animation, giving your advice would be helpful to make people understand benefits.
(the pose animation benefits of PSD seems very great, but explained in plain english would be helpful.)

Do you think one of these techniques might end up in Ogre?

If 'requested', it needs to be properly motivated, even "marketed" so that everyone agree it's interesting.
For instance, about dual quaternion technique: a word saying that ET:QW and crysis does that has some weights.
Proposed help like some artists models or anything is also making points.
I guess hiring sinbad would help too...

If done as a patch, it's much more likely to be integrated

Once proven interest and motivation, you have to wait for sinbad last word on it. It can either end on ogre TODO list or in Gsoc proposal list.