Re-orienting a pole vector

[will-lee]

Hey guys,

So I've actually got a rather simple problem that I can't seem to find a solution for. I'm trying to create an IK leg for a biped character rig, and whenever I do so, the IK tool creates the handle with the Pole Vector pointing into the character's groin, causing his leg to bend inwards (into the other leg). I could create a pole vector constraint and simply move it forward, however that would cause the hip to twist at the joint.

Is there a way to get the pole vector to be created pointing in the right direction? I've tried re-orienting the joints involved (the hip, knee and ankle) but the pole vector always points into the character's pelvis despite what I change them to. I can change the the pole-vector settings after the fact, but as I said, that causes the joint to twist.

[daikath]

Are the bones bent in the forward direction? The IK Handle's pole vector needs a plane. Im having difficulty picturing this, some screenshots of the situation wouldve helped make things clear.

But I think it would be helped with a pole vector constrain. Create a locator (or your favorite control object). Place it to where you want the knee to be pointing. With that object selected, shift select the ik handle, then go into constraints -> pole vector constraint.

[mzahmbie]

You should be able to change the pole vector without using a constraint, it's doable no matter how the leg joints were built, but is much easier if it's built in line with the xyz axes.  If it's built in line with the xyz select the ikHandle, open up the Attribute Editor and expand IK Solver Attributes.  You'll fine the Pole Vector position stored there.  Whichever way your leg is suppose to be facing place a value of 4 in the cooresponding xyz for the Pole Vector and 0 in the other two.  So if your leg should be facing positive Z you'd have 0, 0, 4.  If the leg should be facing negative x you'd have -4, 0, 0.

When an IK is made by default it generally tries to place the pole vector 4 units in the direction the IK limb is bending, towards the elbow or knee for limbs.  If it's still getting it wrong, without more info, I'd just suggest deleting out the joints, remaking them, orient them correctly and remake the IK.  Hope this helps!

[john-david-marte]

You probably rotated your joints into that position, rather than just simply creating them in that position (by snapping into locations). If so, you probably have rotations in your joints. You will need to get rid of this by freeze transformations. This will work be the solution if creating your IK makes your joints snap to that weird direction you were talking about.

Now sometimes I encounter (and could no longer reproduce) issues when creating the IK give me no movement at all, but because of the way the orienations of the joints are, when I bend the IK setup (even with polevector constraints) I the elbow or knee skews of to the side. I just made sure the orientations are all in the same direction and it worked.

Hope this helps!