How to use corrective bones in animations?

[CrimsonHelm]

I have a character that have a very complex skeleton, imported from Maya. Besides the main bones (clavicle, upperarm, forearm, etc), it has various corrective bones for each main bone.

My question is, when working with retargeting animations (from mixamo for example), or with live performances using motion capture suits, how can I use these bones?

[SupportiveEntity]

Hey there @CrimsonHelm! Welcome to the community! I believe you would use the corrective roots as morph targets as referenced by ER in this post:

How to set bone driven controllers for corrective morph targets

I have modeled some morph targets to correct the deformation of the pelvis of a character. In the AnimBP I am trying to set up a bone driven controller so that if the leg rotates in a certain axis up to the 90 degrees it will set the value of that morph target, mapped from 0 to 0 degrees and 1 to 90 degrees. The problem is that I don’t understand how to set the parameters correctly for this node and can’t find any sources on how to properly achieve this. Could I get some help with this?

[Enter_Reality]

Those joints are controlled via a Post Process AnimBP where the Pose Driver node takes care, using a ROM animation, to move/rotate those additional joints, so either using a live mocap performance or in game, those joints are automatically driven, giving you a more accurate deformation compared to standard skin weights from a default skeleton.
If you open up a Metahuman skeletal mesh, you’ll notice that at the bottom of the viewport it says that there is a post process AnimBP, so open it up and you’ll see various Pose Driver nodes and their setup, which is a good reference for you to check if you want a similar behaviour.