View Full Version : creating a rig for motion capture?

05 May 2011, 09:43 AM
my employer wants me to make a test rig for a new motion capture he want to buy.
i never rigged for motion capture and i don't know exactly what should i aim for,
do i need to set controls or just a skeleton?
do i need IK's or not....
i don't know anything about motion capture rigging,,, so i don't know how to approach this.
if it matters the motion capture used is MVN Studio.
please advise.

05 May 2011, 03:12 PM
Are you using the xsens capture suit? If so the data can be very hard to fix/clean up as its all inertia and accelerometer based. (i.e it doesnt know the ground - unless they've fixed this)

As for a rig, what are you content tools? Maya/max, motion builder?

Generally you will build a control rig that get glued to a mocap skeleton - this is a standard skeleton, that programs like motion builder can work with. Essentially you prep a standard hierarchy in a t-pose, arms out, legs/hands flat and send this to motionbuilder as FBX.

In motionbuilder you bind this to a character/control rig which recieves input from an 'actor' this is a standard type in motion builder which basically builds rigid body constraints for each joint based on optical data (TRC). With xsens its inertia based so im not sure.

Finally you export the data from mobo, either as fbx, or a motion format BVH etc to you content tool and constrain your rig back to it.


05 May 2011, 11:15 AM
I have worked on few before....................
i used to work in Autodesk Maya and we had vicon mocap system.............

as i did, we dont need controllers and no ik is just a basic skeleton without any forearm as well. try skinning it to extent level, as mocap rigs are basically dependent on skinning.

05 May 2011, 01:17 PM
Hi, I work for a UK MoCap company called Centroid 3D, and I've handled a few rigs!
The general rule of thumb is the simpler the better, with a clear naming convention and an unbroken hierarchy.

We use Motion Builder all the time and the characterization process relies on the skeleton to have all the joints you would expect in a basic biped rig and named in some kind of obvious way (eg spine joint would be "Spine1, Spine2, etc", legs would be "LeftUpLeg, LeftLeg, LeftFoot, LeftToeBase, etc" arms would be "LeftArm, LeftForearm, LeftHand, etc").

You would send this rig to the mocap company to solve onto, then back in Maya you can use whatever deformation elements you want. As "eek" said mentioned, you could use this basic rig to puppet a more complex deformation rig.

Having said all that, we sometimes receive full animation rigs, and the client requires the mocap solved onto the IK controllers, so any rig can be used for mocap, but the above helps a great deal!

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