Edit over Motion Capture using control rigs?

[satyajit]

Hi all,

Is there any way to edit a skeletal biped rig with tagged mocap data on the bones? I'm not talking about offsetting/ adjusting data or cleaning up fcurves. I'm talking about s.ystems somewhat like motionbuilder, where you can drive the skeletal rig with mocap data with a control rig (FBIK). In this s.ystem the skeletal rig (with mocap data) can be manipulated with the FBIK control rig. Also, the FBIK rig are somehow constrained with the skeletal rig. This is what puzzling me. How can this be done without getting into cycling constraining problems.

Anybody with any idea. How do you edit your mocap animations then?

Satyajit

[Hirazi Blue]

How about baking the mocap into an action source and then mixing
newly created fcurves on your rig, freed from mocap, with the resulting Action Clip,
as described in "Nonlinear Animation > Actions > Mixing Fcurves with Action Clips"?

[satyajit]

Thanks Hirazi,

Yea, it'd be possible to do that. Also we can do that using Animation Layers. You can blend IK and FK (mocaps). But the issue is elsewhere. It's a paradox.

If you want to control the FK chain (plotted with mocap data) by an IK chain, you can constrain the FK to the IK system. But then, how will you make the IK system follow the FK system? Both system can't be interdependent.

I wonder how the FBIK system works in Maya/ Motionbuilder. If it can do this, it should be replicatable in Softimage.

[Mathaeus]

Thanks Hirazi,

If you want to control the FK chain (plotted with mocap data) by an IK chain, you can constrain the FK to the IK system. But then, how will you make the IK system follow the FK system? Both system can't be interdependent.

AFAIK, it's always some kind of caching - layering system under the hood. So, your software creates a copy of both IK and FK transforms, somewhere outside of elevation chain, then you call what you need of that.
Softimage bone chain has some of functionality there - if it isn't enough, you can create separate IK and FK chain, constrain orientation of bones to FK chain, position of effector to IK chain. By switching IK/FK in first bone PPG, you switch between these constrains. Constructions of this kind are working like a charm in Softimage.
Then you use simple scripting to match all stuff together.

BTW, that mocap stuff, also motion re-targeting, seems to be ideal task for ICE kinematics....

Cheers

[Hirazi Blue]

Yeah, I see the problem...
In my defense, I only tried to answer your final question ("How do you edit your mocap animations then?"),
lacking the knowledge to actually answer the first...

[satyajit]

Thanks Mathaeus,

Hirazi, I think Mathaeus got a point. I hoping more ICE Kine knowledge and compounds will be available soon. Because I think it's better to build rigs complex like these around that.

Waiting for the release of SI 2011 SP1. Can't wait after seeing this image.

http://images.autodesk.com/adsk/images/softimage2011_ice_kinematics_large_1400x888.jpg

[Hirazi Blue]

Yes, more practical ICE Kine stuff is needed...
And also some effort should be invested to make ICE Kine slightly more accessible to people like me,
who do not fall in the "advanced riggers and TDs" category the User's Guide mentions.
Okay, that's a bit of a (recurring) rant, sorry... ;)

edit - I however seriously doubt SP1 will bring more than some desperately needed bug fixes.
I'd however like to be proven totally wrong in that respect obviously...

[Mathaeus]

btw, what I described, it's really easy to do *if* switching is left to user, then it can be only something like get value from FK chain > set key to IK chain... even that way of control can be convenient for animations with a lot of IK/FK or constraint switching - sport, fighting, so on.

For mocap with keys on every frame, a slightly forgotten old story about 'Selection Change Command' and that stuff, become attractive again...

[grahamef]

Just thinking out loud -- can you make the FK system a sort of parent or pseudo-parent of the IK system, and then use the IK as a sort of offset from that.

@Hirazi: SP releases don't contain new features. If they did, there'd be all sorts of revenue-recognition issues.

[Hirazi Blue]

@grahamef - As I already wrote how I "seriously doubt"ed it, your answer doesn't really come as a shock to me, but before Autodesk came along, new feature in .0x releases weren't totally unheard of, as far as I can recall.

[satyajit]

@grahamef : Well, you are right. If you make the FK system parent of the IK, you can make the IK follow the FK. But, you can't constrain the FK to the IK system when you have to offset. It'll generate cyclic dependencies.

@Hirazi : I'm expecting full implementation of the ICE Kine system they promised, some serious usage examples (like a production level biped rig) and training mats to transfer the knowledge.