View Full Version : IK'd leg twists odd

05 May 2003, 02:56 AM
Hey, I normally have never had problems with IK legs, but it seems like this file is acting up and even new bones i attach to the skeleton have the same results.

The leg is twisting at the calf and ankle when i just raise the IK vertically. The 'twist' parameter only helps with twsiting the whole leg, while it's the knee & ankle that is the problem....

I have a feeling like i have to set assumed angles (is that the correct term?).

05 May 2003, 05:27 AM
Do you have something set-up for the pole vector? It looks like the knee is pointing funny because you don't have a pole vector constraint out in front of the leg.

I'll give you quick and dirty instructions for how to do this.
Ignore thme if you already know how.

1) Make two locators, point snap one to the ankleIK
2) Move the second locator out in front of the leg, preferrably on
level with the knee.
3) Name the second locator lf_kneePV or something like that and
parent it to the first locator (name it lf_ankleIK).
4) Point constrain the actual ik handle to the lf_ankleIK locator.
Select the locator first, then the IK handle.
5) Pole Vector constrain the ik handle to the lf_knee PV locator.
Again select the PV locator first, then the ik handle.
animation/constrain/pole vector
6) now Hide the ik handle. You should not have to use it again
and it will only get in the way when you try and select the locator.

05 May 2003, 08:14 PM
Pole vectors are the same as changing the 'twist' though. It twists the 'whole' leg, at the hip, not at the knee or ankle.

05 May 2003, 10:01 PM
But when you use the pole vector it doesn't hook to the "twist" arrtibute. It actually hooks to the pole vector rotate attributes.
Is this not the cure to your problem?

05 May 2003, 12:01 AM
Another potential solution to this would be to set up another IK between your ankle and toes...

Then have three locators - one at the ankle, one at the toes, and one above the ankle...

parent the toes one and the above ankle one to the ankle one, and point constrain the toe IK handle to the toe locator. Pole Vector constrain the toe IK to the locator above the ankle

Then, you can control the foot precisely by both moving and rotating the ankle locator...

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