View Full Version : Elbow solution

04-26-2009, 01:35 PM
I'm trying to use a pole item to solve an elbow (no bones, just objects) while using IK on the forearm and upperarm but the results are eratic. I need to create a lot of keyframes to stabilize the elbow movement - this makes it more difficult to edit expressive movements.
Arms are in forward direction with a slight pre-bending down/outward.

Results are fine when using the pole item solution for knees.

So far I had best results when using an extra (shoulder) null as a parent for the upperarm and use that rotation on all three axis to influence the elbow.

Is there a better way?

04-26-2009, 04:56 PM
Generally I use IK on the arms only if the hands need to stick to something, otherwise I just use FK. I would also basically duplicate what you did to solve the knees.
I also tend to use 2D IK on the knees or elbows. In other words Ill use a small bone pointing down the z axis with IK only in the bank to rotate the leg or arm out to the side then the next bone which would be the thigh or upperarm gets IK only in the pitch channel. So between the z axis bone and the thigh/upperarm bones combined I get a universal joint but its generally more stable.

04-27-2009, 12:58 PM
... otherwise I just use FK.
Does FK make it easier for you to make expressive poses and movements?

04-27-2009, 01:27 PM
Yes, no doubt about it. I find myself only using IK on arms when I need some general movement, while walking or limb pinning or quick movements while holding objects in a characters hand.

These are just my experiences though, I'm sure others have different experiences.

04-27-2009, 03:38 PM
Yeah, IK on arms is often not very useful, except when the hands need to stay in one spot...I often setup an arm IK chain, but only use Fk...You are able to be a bit more expressive easier that trying to move the ik goal all the time.

04-27-2009, 06:40 PM
You get the most control with FK. Sometimes you can use IK to get quick placement then use FK for finer control after.

04-28-2009, 10:47 AM
Thanks guys - I'll try FK in the next days and weeks.