In short: Retarget skeleton will have its foot joint bouncing into the air, becasue a joint-to-joint remapping propagete source skelton's pelvis(upperstream)joint.
Setup
The original animation. An Xbot is throwing kettlebell
We can see Xbot's feet are strictly snapped to the ground (Their Y pos value is 0)
Problematic Animation
In FK_Jitter_foot.hip
This time I use luiz to setup up a retargetting network as the manual suggets.
You see if I remap every joint of luiz to the xbot, the output skeleton animation will lift his feet off ground fiercly. I think it is because of the source, the xbot's hips/pelvis joint is using the FK mechanics to propagate its Y position.
Problematic Escalated
In FK_Jitter_foot_worse.hip
I tried to break the remapping links between the hip joints. And tweak the damping/iteraion in FBIK node. The foot bouncing seems to relieve a little bit.
However, if I want to further modify the animation, like moving the entire skeleton to a position by direcly moving the hip joint, the bouncing foot comes back. If I use a IK chain, the problem still exists. It even could get worse, somehow foot joints(as IK goals) could bounce more.
Solution I tried
A. Stablizting Joint Note.
It kinda work in most of the timeframe but the foot joints will bounce fiercly in one or two frame, no idea what happens.
B.I have no idea of what I am doing. It is some sort of joke..I literaly, pin the joint to a coordinate.
Further thoughts:
I am thinking of a solution to reduce the vibration of the foot joints which are supposed to be firmly stick to the ground. Or I want to know how to snap it to the ground so upper stream joint's transform won't propagate its position changes to the end joints.
It is not very enjoyable cause that makes animations like throwing a basketball looks very floaty.
