View Full Version : need help with changing joint in ik in maya please!

03 March 2010, 03:43 PM
i already made a rig for a dinosaur earlier and now i want to reuse it on a another dinosaur i made.
but the lengthe of the arm doesnt match and i cant move it correctly because of the ik setup.
is there any way i can change the joint without losing the ik?
i would highly appreciate your help.

03 March 2010, 07:55 PM
can i turn off the ik temporarly, make my change on the joint and get the ik back without having to make it new?
or something like that would help.

03 March 2010, 03:21 PM
you can resize the length of your joints. For example taking the elbow and go to the attribute editor than using translate X to lengthen or shorten your joints. After that just snap your IK back to the wrist. It should works fine.

03 March 2010, 06:02 PM
thank you.
but can i reposition them aswell?
like the shoulder isnt where i need it to be.

03 March 2010, 06:58 PM
as long as you select the root joint, you can just translate it around to fit your new model.

03 March 2010, 08:31 AM
thanks but it doesnt work very well when i tried it.
if i move it too far away everythings screws up ...
and the spline i cant even move at all.
is there no other way then doing it all again?
im not good at rigging ... :/

03 March 2010, 01:51 PM
you can turn off IK at any time by setting the attribute "IK Blend" to 0 (Zero). This attribute is on every IK handle.

That said. If you are still new to rigging and learning. I would suggest removing all the IK chains and redoing all the IK and control setups from scratch. It will help you more in the long run. When I am doing some newer rigs I will redo the Rig 3 or 4 times just to get my technique down a bit better. It also helps me see how I can improve a given process.

04 April 2010, 04:57 PM
I agree with Darksuit: Even if you could keep an IK handle intact and working while moving joints, I would not trust it.
When you make an IK handle, its solver looks at all the joint data and sets up the handle for you.
Even as a somewhat beginner, the making of IK handles is very quick, so don't be afraid to rip out IK handles, move the joints, and then remake the handles. Not a long process.

Good Luck

04 April 2010, 09:43 AM

I noticed that I am no longer able to reorient my joints (via skeleton->orient) once I applied an IK chain and moved the IK handle (that even applies if I move it back to its original position after moving it elsewhere). Why is that? Is there a way to circumvent that?

Practical example: I have a fully set up human leg and find that the knee should be further up or completely repositioned: What is the most logical step to take with the least amount of superfluous work to put into it?


04 April 2010, 07:36 PM
The orientation of a joint when IK is applied is controlled by the IK. For a standard IK chain you will use the Pole Vector to control the orientation. For an SC chain and IK Spline you would use the Roll Attribute.

This is however much different that the example you cite. The example given has nothing to do with Orientation but with translation. You can turn off the IK blend attribute. Then with the IK off you can translate the Knee into the correct position. If I need to do this, I will unparent the knee from the ankle and from the Hip/Leg. Move the Knee into position then reparent everything back.

My core suggestion is still and will almost always be to just rebuild the IK chain. It doesn't take that long and if you really need to you could script it out in MEL or Python to just auto create it.

04 April 2010, 10:08 PM
Yes I got friends with the thought that I have to redo the IK chain now but one problem remains. I cannot reorient my knee (to face the ankle) after I moved it into position (following your instructions about the unparenting plus deleting the ik chain) - I mean I could go in and turn their orientation by myself but the maya implemented script from the menu skeleton->orient does not work. It's error message is e.g. "// Warning: Skipping joint2: It has non-zero rotations."


04 April 2010, 08:36 AM
Check joint 2 in the skeleton chain and see if it has any rotations in the channelbox.

I also had a problem at some stage that all the rotations in the channelbox were 0, and I still got the error.The reason for this is that Maya sometimes has very very small rotation values on the joints (i.e 0.00001) which get rounded to 0 in the channelbox, but in fact the joint has non-zero rotations. I then manually set every rotation to 0 and it worked then.

Hope that helps.

04 April 2010, 07:36 AM
That helped! Thanks!

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