Retargeting research

I wanted to experiment with retargetting motion with constraints from one joint chain to another but as I don't have the motion capture data I'd need yet I've set up some simple tests in Maya.

Firstly I've decided to just try applying movement from one joint to another without any complex rigs in place but then I think it would be a good idea to try and apply the movement to the lamp rig just to check the rig doesn't interfere or vice versa.

I've set up three tests: Uniform movement translation, non-uniform movement and then this multiply node that reverses movement to just double check it does what Norbert says it does (which i don't doubt) but also to check i know how to use it.

First test I've used a parent constraint which seems to work fine so long as you  have the joint chain in the same position as the source but if not then limit the constraints to just the rotation planes, having translation causes the entire joint chain to move and gives undesirable results. And if the joint chain doesn't match the orientation of the joint then again undesirable results are seen in the path of the movement...

I've been reading a paper by Hsieh, Chen and Ouhyoung from Taiwan University:

http://graphics.im.ntu.edu.tw/docs/cadcg05_hsieh.pdf

 Which actually looks at retargetting to different articulated figures and it looks like the best solution they came up with it to make a transition skeleton. This takes away the issues that were had with trying to retarget to a bone with a different orientation. They combat the difference in quantities of bones that make up the skeleton by applying the same motion from one source bone to many target bones. 

They create the skeleton by re positioning each target bone of the transition skeleton to align with each source bone.

While they do align the bones core direction they do not consider the twist in the bones which can lead to some unexpected results.