View Full Version : Jittering bones

07 July 2005, 07:11 AM
I'm having a problem with bones jumping all over the place. I've set up IK for the soon as I move the Goal Nulls, the bones start to jitter like crazy.

any ideas...I'll post the bones if anyone want's to play around with it.

07 July 2005, 07:33 AM
Make sure you terminate the IK chain by making the root of the chain "unaffected by Ik of descendants". Also it can help adjusting the stiffness and setting up IK rotational limits. Do you use any motion modifiers like Cyclist, follower etc?

If you want to, I'd like to take a look at it...

07 July 2005, 07:51 AM
Yes, "unaffected by Ik of descendants" has been ticked on both pelvis bones.
The bones follow the foot control Nulls, but the jittering is just damn frustrating.

The funny thing is that when I move the control Nulls slowly, the bones do not jitter at all

I will post the rig as soon as I'm done with a test render.

07 July 2005, 08:35 AM
here is the rig. I used "RV_Rigtools" on the Spine. I've used it on many other characters and it worked fine...maybe I did something wrong.

Move the foot Controls around or rotate will see what I mean.

07 July 2005, 10:11 AM
Hi Werner, i tested your rig and the first thing that i found is the rotated legs bones (B_R_Tigh and B_R_Calf , same thing with left side)... The B and P axis is on the gimbal lock position and P axis is actually pointing on wrong (diagonal) direction. U mast fix it - try to make Pitch parallel to World Z .
Second thing, is lack of prebanding on the knees (i don't know what kind of character u have but the knees are banding backward). I usually add additional goal for the knee (straight to lower leg - B_R_Calf in your case) with weary low strength 1-5 , this goal act like pole vector and try to drag knee forward.
Hope this will help ...

07 July 2005, 02:16 PM
Thanks Eugeny! I'll make the changes and will let you know if it worked.

Always good to see you around...thanks again. :)

doc sampson
07 July 2005, 08:32 PM
turn off "keep goal within reach"

07 July 2005, 11:40 AM
Pre-bending the joints is surely necessary. Also, to keep legs "tighter", and from flipping backwards, you should have a very small knee bone between the thigh and calf. Turn the stiffness up to 10.


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07 July 2005, 11:40 AM
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