CGTalk - To IK or not to IK?

kennez

12-07-2004, 09:59 PM

I am currently rigging a human character for a short I am working on, and I cannot decide if I need IK for certain parts of the body.

I have IK on the legs and arms - so far so good. The problem is, I don't know whether I need it on the spine and hands.

For the scene I am rigging the character for at the moment, she wil just be walking down an alleyway, possibly holding something (I haven't quite decided about that yet).

The rig is a fairly straightforward one, featuring a leg setup similar to the one in the tutorials, and a simple IK arm setup similar to one of the sample rigs included in the content. The spine has 6 bones, plus three in the neck (I like a fair bit of control for the back and neck).

This rig may be reused in future scenes, but for more complex motion.

Any dvice would be greatly appreciated!

Dennik

12-07-2004, 10:58 PM

Personally, i'm strongly against IK for the arms, except for the situations that the palms are pressing against a surface, or they are holding a door knob. For every other case, FK is the natural way to go. Because the real arms are by default FK! So if you have the time to implement an IK-FK solution, that would be the best (and its quite easy with Messiah as well)

Spine can get very unstable with IK, unless you make something simmilar to Isner Spine (http://www.isner.com/isnerspine/spine_introduction.htm)
which might actually work.
Ik for fingers can work as well, use the last finger bone as the ik handle, and parent that to the wrist bone.

And one last thing... For dynamic parenting stuff to your hand, the fastest way till today is still the hide-unhide trick. :) good luck!

AlexK

12-08-2004, 06:02 AM

And one last thing... For dynamic parenting stuff to your hand, the fastest way till today is still the hide-unhide trick. :)
I like the DynamicParenting expression as well. I works maybe even faster because you have only one object to care about and therefore see where it is. Whereas with two objects you have to key two opacities, which doesn't show up in the openGL view (which means you have to render to see if you set your keys correctly).

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