how do i reduce knee pop

Hi Tobe.

Knee pops are hard.  It's actually one of the bad things about getting better at animation.  Once you see them, now you can never not see them haha.

They occur when the knee goes from straight to bent to fast (or vice versa) and it's an inherit problem with IK.  (it's because the rotation acceleration on both joints approaches infinity - picture a Tan curve that flies off to infinity and then comes back again)

The cause in the animation could be many things, maybe the heel needs to raise or lower a little bit, maybe the hip is too far away from the foot, maybe the foot is too far away from the hip or too close the hip- the list goes on.

Ideally you need to look at the animation and figure out what the cause is, and then try to remedy it.  Sometimes you just can't.  And that is where the "Knee_bend" controllers come it.

You can key move the position on the knee over a few frames to soften the pop.  But you want to make sure you do this as a last resort or when you need to intentionally 'break a joint'.  And make sure you key frame it at its default position before and after this edit.  Otherwise you will will break the rest of the animation because the knee joint will be out of place.

Hope that helps.