plugging a bvh mocap into a non-mocap (rig with controllers) rig?

[Adam Trachtenberg]

Cineversity has a six-part series on doing just this, but I think you probably have to join (pay subscription) to view them. The way they do it is VERY involved. Not sure if there’s an easier way, and it’s too complicated to explain in a forum post.

[Manojit Ghose]

Hi Adam,

thanks for the pointer, i will look into cineversity.
by the way have you tried this process? i know i am probably asking for too much, but in case you have a file which you could share, i would be very grateful.

thanks

MG

[Adam Trachtenberg]

I watched the tutorials but I never actually tried it out. I was looking for something relatively simple, like Motion Builder used to be, and but the time I got to video 5 of the series I realized that this wasn’t it.

[Cactus Dan]

Howdy,

One of the problems with applying motion capture to a rigged character is that the imported motion capture skeleton may not have the same joint twists as the skeleton to which the mesh is bound.

The easiest ways to handle it is to create 2 joint skeletons for the character. One rigged normally with IK and constraints, etc., to which the mesh will be bound, and the second skeleton to be used as a driver skeleton for the first one. What I mean by “driver” skeleton is that within that second skeleton, parented to specific joints will be target nulls to which the IK goals can be targeted, so that the second skeleton can drive the IK of the first skeleton.

You would then retarget the motion of the imported mocap skeleton to the driver skeleton, which will in turn drive the IK skeleton.

Here is an example of a driver skeleton driving an IK skeleton with a blend between the 2:
https://www.cactus3d.com/bvhBlend.mov

… and an example with a bound mesh:
https://www.cactus3d.com/bvhExample2.mov

It takes a little work to get the initial rig set up with the IK and driver skeletons, but once that is done, that can be your standard rig from there on out.

Adios,
Cactus Dan

Cinema 4D R13 Prime
http://www.cactus3d.com
http://www.cactus3d.com/Plugins.html

[Manojit Ghose]

hi Dan,

thanks for the answer,
i am wondering if there is tool to automate the process, or everything has to be done manually (actually i am not a rigger, just using the off the shelf stuff from the character module)

thanks

MG

[Cactus Dan]

Howdy,

You’d probably need to convert the character module rig to a fully editable rig and then manually set up the driver skeleton.

To set up the driver skeleton you’d first import a T-pose skeleton that matches your mocap import. Then create dummy NULL objects for each IK driver target and parent them into that T-pose skeleton. If your IK chains are targeting the rig controllers, you’ll need to create another set of NULL objects to serve as the actual IK Goals. Then constrain those IK Goals to the controllers and the IK driver targets. You can add a User Data slider and Xpresso setup to create the blend between the 2 targets in the constraints.

It will be a lot of work, but once you get it done, you can probably reuse that rig for other characters.

Adios,
Cactus Dan

Cinema 4D R13 Prime
http://www.cactus3d.com
http://www.cactus3d.com/Plugins.html

[Cactus Dan]

Howdy,

Oh, I forgot to mention that you also need to do the same thing for all the IK Pole Vectors.

Adios,
Cactus Dan

Cinema 4D R13 Prime
http://www.cactus3d.com
http://www.cactus3d.com/Plugins.html

[Manojit Ghose]

hey dan,

thanks for your answers.

MG