View Full Version : IK Flickers

Dick Ma
02-27-2003, 07:41 PM
I set a walk cycle for my character animation and I discover that my leg IK chain flickers when the goal doesn't always follow the motion path.

There is only one goal null for each leg, and in the leg bone two IK are set on H & P. the foot bone IK is set on P only. The IKs has set angle limits.

It is so obvious that the flickering happens in the knee area......

Any tips to solve this?

02-27-2003, 10:12 PM
If you turn the thigh bone heading back to keyframe you can key that rotation so the knee stays where you want it, I think.

Or...you could make the shin bone a goal for the thigh bone and adjust the goal weights till you get the movements you`re after.


Dick Ma
02-28-2003, 03:47 AM
Oh... I would like to try to set IK or FK blending.....I have tried IKBlender Plugin but the plugin is quite disappointed because limit settings will be removed and cannot set specific channels to be IK or FK blending.

Didn't learn how to write the expressions...(Math idiot.)

02-28-2003, 04:35 AM
Mmm: me too!



02-28-2003, 08:38 AM
try upping your goal strength to 100

Dick Ma
03-05-2003, 10:58 AM
Increasing strength helps a little but...IK still flicker....

First I made a null act as a "pivot" for the character.

two legs null fixed at y= 0m

when I move the pivot null down when the null is still fixed at 0m
the knees area still flickers......

03-06-2003, 08:37 AM
I had that problem once and found out it was related (on my setup) to Bones angle limits. In an IK chain, considering a bone and a child bone, if the child limit angle for pitch (for instance) is 180 you may have flickering: Near the limit the leg tends to snap to the straight 180 position while IK commands another position. In such a case giving 179 as pitch limit solves the problem... Do try that!