Preserving Motion Through Retargetting (Proposal breakdown part 1)

This will be quite a long post outlining the work I did researching for the proposal. (I might split it into a few posts) I generally used my notebook to keep track of ideas rather than my blog which is why it has been a bit neglected however my notes are a little all over the place so I'll do my best to keep it from being confusing.

The main sections for my literature review were as follows:

• Preserving motion through retargeting
• Physical Props
• Acting and Key Poses
• Lattice deformations and Spline IK
• Spasm: Procedural Animation and real-time retargeting.

1. Preserving motion through retargeting.

Gleicher - developed a solver which preserved desirable qualities of motion using space time constraints to allow interactive control of animation via UI. The process described in the 1998 paper delivered as part of SIGGRAPH '98 initially uses the angles of the source characters joints to drive the movement in the target character however this leads to problems when the character is scaled as shown in figure 2 taken from the journal itself. 

To fix this he used IK solvers to help apply constraints to the characters feet, forcing them to stay planted but as IK solvers consider each frame independently it doesn't know what the motion is in relation to the frames around it resulting in "high frequency jerkiness".

Spacetime constraints: (Witkin and Kass 1988) uses 3 factors to help dictate the movement needed. What the character needs to do or the mechanical action of whats being moved so from one place to another or onto something etc, How it needs to do it so characteristics of the movements. and also how the physical structure of the character would affect the movement for example how the joints are able to move, what the mass of the character is etc.

Main problem Gleicher had was that despite being able to replicate the movements of the source character it took out all personality. 

Gleichers work may be beneficial in transplanting movements from source to target for replicating the mechanics of the movement but when retargeting to a target that has a different structure to the source then I would have thought a little flex from the original movement might be useful but then again with space time constraints one of the factors is the physical structure of the character which could either break the movement entirely or cope with it.. Might be a useful thing to look into?

Moving Forward
I mentioned in my dissertation about unity's mecanim and Mayas human IK, both these tools focus on the retargetting side of things specifically. I feel like exploring the possibilities these two processes offer would be in my best interest so I'll dedicate a post specifically to research into their capabilities hopefully resulting in pipelines specific to those.