View Full Version : IK twitching

08-16-2006, 03:52 PM
So can someone explain to me what is happening here...

I have attached a scene file with an IK rig set up. I've taken out all the objects and just left the skeleton in tact. When I am animating the scene I get this wierd twitching in the bones. I can't seem to figure out what is happeing here.

Can anyone help me out?

Thanks in advance!

08-16-2006, 04:23 PM
This is a known problem with the IK system in LW. The solution is to use somekind of baking, to bake in the motion. I'm not very familiar, but there is a site that will help you with it. http://www.ikboost.com/

Hopefully, in the 9.x cycle, they can just make it rock solid stable without the use of motion baking.

08-16-2006, 05:05 PM
To be more specific, the problem is that your character is too far away from the zero point. If you keep it within say 50 meters of zero, the problem should diminish significantly. The closer it is to zero, the smoother it will be.


08-17-2006, 07:23 AM
Thanks for the tips. I have that character in a very large landscape that I created, but I moved the whole thing and the problem went away. I am very interested in the IK Boost stuff though, but can't seem to get the videos to play in Quicktime. I'll have to contact them directly.

That was very helpful. I knew there were some smart people in this community.

08-18-2006, 02:43 AM
Thats been a longstanding issue in LW for a very long time. Ive found that you can expect reasonable results if you keep your rig within a kilometer or so of the origin. Otherwise LWs IK is stable, IF... you set it up properly. :)

08-18-2006, 04:17 AM
I wonder if this is simply the result of limitations in mathematic accuracy for 32 bit hardware. Trying to have sub-mm resolution when evaluating a world that is 10^6 times larger could be really pushing things.

It would be interesting to find out if this is 'fixed' under Win64 with LW 64-bit, but I don't have such a system :)

08-18-2006, 06:13 AM
Try the IK motion modifier plugin you can find on this page ( plg_ik ). It seems much more stable then LW's IK.