Just came across an issue I’ve not seen before, and wanted others opinions on other ways to fix it.

One of my animators collapsed 1 abs layer and 2 relative layers into one Collapsed layer, worked with it all day, and suddenly the Leg IK started freaking out. When the IK handle was moved the Leg wobbled every which way, as though trying to figure out the best IK solution. Even turning on the ‘Use Up Node’ option did not help.

I finally had to delete all animation on the handle, collapse everything to a new layer, then turn on the ‘use up node’ option to get the Ik to work properly again.

Anyone have an idea as to why this would happen? and how I can avoid it in the future? also, any other solutions that don’t require wiping out animation keys?

thanks!

-ian

Yes, there are certain situations where the IK solution does not work properly. Somehow you have introduced rotation keys to the limb bones although you are using the UpNode. You can do that in order to fix deformation issues or something like that, but normally the limb twisting should be controlled by the UpNode only. These bad rotation values cause the limb to drive crazy.

Anyway, if you have bad rotation keys on the limb bones, get rid of them by deleting them in the track view and assign the default rotation values from the Setup Mode. This should fix your problem without having to delete existing animation.

My CAT demoreel:
http://www.youtube.com/watch?v=Gfq-4VoeAPU

I thought that might have been the case, but there are no keys on the thigh and calf bones on the collapsed layer. There were rotation keys on the layer above it, and i am guessing that when the animator collapsed the layers, that those rotations were collapsed as well, then the keys were deleted,and that’s what messed up the rotations. it’s just a guess though.

thanks for the help Gräck!

-ian

Are you sure you have the same rotation values on the limb bones as in Setup Mode? I’m talking about values here, not keys.

My CAT demoreel:
http://www.youtube.com/watch?v=Gfq-4VoeAPU