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Root Motion Support

I use 3DS Max and am using a CAT rig for my humanoid.

As I understand it you need an extra bone at ( 0, 0, 0 ) that you parent your skeleton to in order to allow for root motion. I have done that, however, when I apply CAT Motion Layers (procedural movement animations, a great time saver) the root bone just bounces around like crazy. I’m assuming this would totally prevent any root motion as my character would be wobbling up and down.

What’s the workflow here?

Is there a way to prevent CAT Motion Layers from effecting the root bone so it stands still?

Why does the root bone in the UE4 documentation (https://docs.unrealengine.com/latest/INT/Engine/Animation/RootMotion/index.html) seem to be parented to his pelvis, his ankles, and his hands? Doesn’t it only need to be parented to his pelvis?

CAT rigs include a large platform with an arrow on it that your character stands on. This acts like the root bone for your CAT rig, and all bones move with it. Is there some way to export this as the root bone?

Thanks!

Ok, so it turns out you can create a Motion Extraction Node from the CAT Parent node (the big arrow your CAT rig stands on) by following this:

http://download.autodesk.com/esd/3dsmax/cat-help-2010/index.html?url=WS73099cc142f48755-5c83e7b111fde81a7425f97.htm,topicNumber=d0e1308

So, that can act as a root bone for root motion I’m fairly sure.

I still have no idea why the UE4 documentation root node is showing as connected to his pelvis, ankles and hands however.

I think Epic uses root node (sometimes) to directly point to hands/other parts for their animating practice. For example, for hands, they use one node connected to root to specify from where the shooting occurs. I think they can scale the mesh and do all sorts of animation retargeting (using the same animation on different character that have, for example different distance between their shoulders) but still keep this node in the correct position. Then they use IK system to drive the hand to that location when the character has 2H weapon equipped. If they would not use IK in this case, characters with wider/narrower shoulders would not be holding two-handed weapons properly. They use same kinds of systems for other parts. Also, they can use additive animation quite easily in this setup.

Anyway, I just add RootMotion bone to the mesh and attach the 3ds MAX character rig to it. When exporting to other characters/reusing animations, I do not transfer that bone and everything works … to some degree. Minor tweaks are usually necessary. Hope this helps!

I had the same problem in getting the root motion going. I have written this in another thread:

“For anyone else having a problem with getting the root motion working, the root bone has to be completely on top of the hierarchy (at least no other way worked). Also, the root bone has to be directly under the “Hips” bone (in the world), just moving in the XY, not the Z. Basically, cannot be moving upwards or downwards. Because I animated the character with the root bone fixed in the origin of the world, I had to redo this, easily by selecting “hips” and “root” and using the “Point Constraint” in Maya LT. This fixed the root bone under the hips bone. Attaching an image of the hierarchy.”

e.g. the root bone is not at 0,0,0. It’s under the character.

link: https://forums.unrealengine.com/showthread.php?78242-Root-motion-for-cut-scene-style-animations