Bake IK to FK

Hi, I’m having issues with baking my IK animation to my FK character Rig. I saw that one method is to bake the animation with “Visual Keying” and “Clear Constraints” selected. However, this isn’t working for me. My animation bakes but the transforms of the leg IKs do not transfer to the foot/toe’s positions so if I try to delete the IK afterwards, my animation breaks. Do you know a method of baking an IK animation to an FK rig? Thanks.

For better clarity, I want to transfer the transform of the IK joint (circled in the image) to the relative transforms of the foot and toe joints. When I bake the animation, the toe and foot joints are empty.

That leg looks posed, but the bones don’t have the colors that would indicate constraints. Is it post-bake or pre-bake?

Good eye. Yeah it’s post baked. This was my ninth attempt baking it.

So it’s post-baked, and it’s posed appropriately-- to the IK. What’s the problem?

I want to delete the IK joints so I can export the rig to my game engine. In order to delete them I need to bake the positions of the foot and toe joints. However, when I bake the animation the foot and toe joints don’t receive any positional data.
post baked and deleted

This is what happens when I delete the IKs and pole targets. The feet/toe bones aren’t having their visual data baked into them. I read that you need to select “Visual Keying” and “Clear Constraints” in the bake menu but that solution isn’t working for me.

So that pic is the same as the last pic, but the only change is you deleted the IK targets and pole targets?

In that case, probably, the issue isn’t with constraints, which are being written appropriately, but with parenting, which doesn’t disappear with visual keying. Your IK targets should not have any children. You may be parenting your feet bones to your IK targets, in order to acquire your IK targets’ rotation onto the feet, which is not very standard practice. Instead, parent the feet to your shin bones, and give them a copy rotation constraint targeting the IK targets.

It should be safe to edit your existing rig to that (before the bake). Shouldn’t affect any animations. If I’m reasoning through correctly at least.

If that’s not the case, I’d have to see a file to say anything else.

So you were right that my foot and toe joints were parented to the IKs. I deleted their parents and re-parented them to the shin bones. It broke my animation obviously but the bake is working correctly. I then added the copy rotation restraint and I can see how this workflow works. I’ll have to redo my animation but everything seems to be working well. Thank you I really appreciate it!

I don’t think you’ll have to redo your animation. If you link a file, I’ll see what the problem is.

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Thank you, but you don’t have to trouble yourself. When I copied the rotation of the IK to the foot, it made the foot twist to the IK’s rotation. So I just need to adjust the IK rotation to match where the foot was originally. Not a total “redo” just a fix for a few things.

Oh right, you probably don’t want to copy rotation directly from the IK target, because its axes aren’t the same as your foot, but from a non-deforming duplicate of your foot bone, parented to the IK target, copied in world->world space (probably, in “before original” mode.)

Oh, I see. That’s a really good idea. That way I still have the heel IK’s position. Nice, thank you for the tips. I just switched from Maya so I’m still learning the ropes but so far I’m amazed by the non-destructive functionality of blender.

Glad to hear you’re good. Generally, when I make an IK target, I just make it out of a duplicate of the foot (or whatever) for precisely this reason:

  1. Duplicate foot bone. Unparent. Disable deform.

  2. Select duplicate foot, shift select shin bone, shift ctrl C->IK, set chain length.

  3. Select duplicate foot, shift select foot bone, shift ctrl C->copy rotation.

  4. Select original foot, m alt 9 enter :stuck_out_tongue:

Actually, I guess I give the foot a damped track to the IK target tail afterwards, just how I like to roll, but that’s a matter of taste.