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View Full Version : Ideas for Knee / Elbow pole vector rigging methods


SkullboX
07-18-2008, 07:06 PM
I'm currently building a new rig I'm designing to be as easy and intuitive as possible to animate, basically to make it faster and a lot more fun to animate. It's turning out pretty good so far, but I dont really like how the knees and elbows are currently controlled (in IK, with stretch), which is the standard pole vector constraint solution.

The problem is that I don't really have much idea's for any alternative, though currently I'm thinking of animating the pole vector manually somehow using an extra attribute on the foot controller, since I'll be animating mostly by hand anyway.

I was also thinking of somehow making a fully 'manual' knee control, working with stretchy IK, which would let me reposition the knee without affecting the position of the foot... so I could for example still bend the knee a little even though the leg is actually stretching passed its limit. While I have a pretty good idea how this could be done, it still won't fix the pole vector issue.

However I'm very interested in trying out other methods, but my rigging creativity is letting me down at the moment. I'm very interested in any tutorials that cover different approaches to rig the IK pole vector, or perhaps any rig with an unsual knee or elbow setup you might have made... or perhaps the pole vector constraint is the best option.

Thanks!

Boucha
07-19-2008, 03:58 AM
Hi there,

This can be really wonderful post.

There are two methods that I use, which the animator can toggle or blend between:

a. Usual pole vector constraint method...
b. No - flip setup

b. No - flip setup...

- Create a joint chain, eg. hips,knee and ankle...
- Create a rotate plane ik solver from hip to the ankle...
- Create a control object for the leg and parent the ik handle to the controller...
- Add float attributes called knee Twist and offset (default value is 90 for the offset) to the controller...
- Set the values for
a. pole vector x = 0.1
b. pole vector y = 0
c. pole vector z = 0
- Now the knee has flipped 90 degrees so add 90 in twist attribute of ik handle...
- Create a plusMinusAverage node (createNode plusMinusAverage)...
- Open the connection editor...
- Load the controller in output and plusMiniusAverage node in input...
- Connect knee Twist to input1D[0] and offset to input1D[1]...
- Connect the output1D of plustMinusAverage node to the twist of the ik handle...
- no - flip setup is done...

SkullboX
07-28-2008, 03:55 PM
Sorry I must have missed this. thanks for the mini tutorial, that was indeed the setup I was hoping to build. After having done some test animation/posing with the previous version of the rig I've really come to hate the IK solver constraint in this setup.

Thanks again!

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