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I am wondering if i could get some tips from the wonderful people of this group. Does anybody have any experience working with CMU Mocap animation? I am currently working with bvh files.

I have a rig already setup(rig assembled by a add-on called auto-rig pro) to which i am trying match the bones of my rig to the bvh. Auto rig pro has a remapping function for bvhs which I'm using but i get errors with this. The most common is twisted limbs and jittery animation.

I'm confused about the rotation of these bones and how to fix them of if i should use ik or fk when remapping.

Also I am researching how to fix the rest pose of the bvh armature, so that the mapping of the bones would result in a better animation but that lead to errors.

I tried using @batFINGER's script for resetting poses and all the post he did so far but I'm getting nowhere or at least i don' think I'm following it right.

Can anybody help? Thank you.

First Example

Remapped using Auto Rig Pro add-on

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  • $\begingroup$ My link is for two rigs with same bone structures. My bvh addon "mocap madness" which was basically targeted to CMU is a long way on the back burner. Often addons (if hosted on github for example) have an issues page. It appears the wrists may have a 90 degree roll. Consider posting a simplified blend to blend-exchange.giantcowfilms.com. Include bvh rig, target rig and say 10 to 20 frames of an action where issue occurs. Also, welcome to BSE. Upvoted (cos it's a good question, not just cos i got a mention lol. (If I've used the wrong link please change) $\endgroup$ – batFINGER Mar 23 '19 at 4:08
  • $\begingroup$ Thanks for the reply. I changed the link because i was talking about the post for just changing the rest pose. the bvh and my rig have way different structures. i tried searching on the add-on’s github page to no avail. i can send you the blend but i don’t know how much info you will get because of the auto rig add-on. The add-on I’m using is basically like the mocap remap tool that you can find on the plugin page. Everytime i remap the bones the errors happen $\endgroup$ – Dominic Keeton Mar 23 '19 at 5:23
  • $\begingroup$ Here is the blend file. $\endgroup$ – Dominic Keeton Mar 23 '19 at 5:44
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I have been wrestling with similar problems and I may start my own question, but in the spirit of cooperation and helping this is what I have found:

  • Rigify and Blender rigs do not work with CMU (without fixing the problems you mention)
  • Daz 3D rigs also import via FBX unreliably. The best way to get Daz characters into blender for animation is to bring them in via .dae (collada) and then exporting via obj or fbx and use mixamo for animations and for auto-rigging.
  • You can then retarget mixamo rigs using "bvh retargeter" to CMU - though not reliably. (https://diffeomorphic.blogspot.com/p/bvh-main.html)
  • N.B. you often get errors "rot & scale" when using bvh retargter. Do not use "transform rot and scale" - ONLY transform scale, otherwise you will get messed up results.
  • If using MB-LAb, it has it's own bvh importer and they work well with ACCAD bvh - but not so well with CMU. Do not use bvh retargeter.
  • If importing from MakeHuman, make sure to use the CMU skeleton.
  • Do not use FBX from MakeHuman to Blender, use the .mhx2 MakeHuman format and get the add-on for Blender for importing MakeHuman assets. You will get a perfectly compliant rig for CMU and BVH retargeter works perfectly with it.

Further notes;

  • The "rest pose" can look messed up, even though the "pose mode" works fine. I don't know why. In fact, avoid rest mode altogether unless someone else can bob and up tell us what it is useful for and when and why to use it.
  • Often the bvh's come with a T-pose at the beginning of the animation - it's best to use that, say for adding assets to a character.
  • "Daz Friendly" bvh's from cgspeed repository don't seem to work - in any configuration I can find, including with Daz 3d studio itself.
  • If you are struggling to parent an object to your character, you have to be in object mode with the armature in pose position then; object>select armature>switch to pose mode>select bone>parent to bone.

I hope this helps someone. I sure could have used this a week ago. It's a pretty convoluted situation.

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