View Full Version : IK On/Off affects bone positions

08-08-2008, 02:27 AM
Hi there,

I have a quadruped creature with a full rig and IK set up.

It all works nicely except that when i turn IK on some of the bones move away from their goal objects slightly. This deforms the mesh a little in its rest position on frame zero and while its not a catastrophic error it is irritating me.

The bones that move most noticeably are the ones in the trunk (ok It's an elephant). The trunk has seven bones, the top one is parented to a large bone in the head and is set to be unaffected by IK of descendants. It looks like the next bone in the trunk hierarchy is rotating slightly when i turn IK on.

I have tried going through all the bones doing "record piv rot" and "Record bone rest position" but it has made no difference.

I haven't even set up any animation frames yet, i want to get a stable rig working on frame zero before i go any further.

Any comments on this would be much appreciated chaps.

08-08-2008, 09:23 AM
Do you have any other motion modifiers, expressions, etc etc on any bones?

08-08-2008, 09:35 AM
This can be difficult with certain IK chains. The best way is to make sure you have good clean keyframes on frame 0 (your rest pose). And if you ever need to rest them again you turn off enable IK global. ReRest your bones and turn IK back on.