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VOO
02-10-2006, 08:44 AM
Iím fiddling with set ups for IK rigs and on a couple of joints when I set up a pole vector constraint it flips the joint because for some reason the joint plane indicator is pointing in the wrong direction to where I want it to. All the joint orientations are the same but for some reason the joint plane indicators are different.


Is there any way I can change the orientation of the indicator plane without effecting the joint like you can with the bone orientation? So its facing the direction I want to attach my pole vector constraint.



Iíve not come across this problem before.


Thanks

M.E.L.
02-10-2006, 06:36 PM
on your IK handle you have a Pole Vector Direction attribute, set that to the axis you wish the vector to solve across (it can be a 1 or -1 or 0). Also make sure your transforms are frozen on your pole vector and that it is translated a fair distance from your chain to allow for a decent solving plane.


-s


p.s. don't forget to snap your pivot to the center of the controller, not to your chain... this can cause some weird behaviour.

VOO
02-14-2006, 11:47 AM
Thanks, but I have constraints on the joints and this wants to effect the joint/ik handle rotation, I want to define which plane the pole vector is created on without effecting the rotation of the joint.

Any ideas?

isoparmB
02-14-2006, 12:19 PM
I think you have to set preffered angle on your joints to avoid this. I encountered the same problem setting up RP solver IK's on every joint in a spine (for divine spine).

The problem becomes accute on joints which are pointing straight up relative to worldspace, and also when you are applying rp Ik's between just two joints, I guess because maya has a hard time figuring out how they would bend.

Setting the preffered angle before IK-ing should fix it.

VOO
02-14-2006, 01:31 PM
Thanks, I apreciate your suggestions, but it didn't fix it either.

It seems wierd it is such an issue? you know how easy it is to reorient a bone.

M.E.L.
02-14-2006, 06:01 PM
do you have a screenshot?

normally the poleVector will only rotate your joints if they are not properly oriented and all aligned right. You'll notice this if you repeat the poleVector creation over and over by repositioning the PV object until you find the "right" placement... I'd check to make sure your constraints and other bits haven't wacked out your orientation... as a rule of thumb, always do your IK/PV stuff on clean joints before constraints and other connections.


-s

VOO
02-15-2006, 02:24 PM
OK. Thanks

isoparmB
02-20-2006, 04:31 AM
I think you have to set preffered angle on your joints to avoid this. I encountered the same problem setting up RP solver IK's on every joint in a spine (for divine spine).



The problem becomes accute on joints which are pointing straight up relative to worldspace, and also when you are applying rp Ik's between just two joints, I guess because maya has a hard time figuring out how they would bend.



Setting the preffered angle before IK-ing should fix it.



Ooops. Have tested it out and it dosen't work either. Hmmmm.



What I did find out is that the root joints which have the problematic pole vectors seem to be doing it because of gimbal lock. You could test this out by temporarily parenting your root joint to the world (if it isn't there already) and checking the joint rient values. Try imputing these into a null or empty joint's rotation values and test the rotation. Voila. Gimbal lock.



I suspect that maya has a hard time placing rp IK's on single joint chains with joint orient values that produce gimbal lock. I don't know if this also affects joint chains with more than two joints.



Still looking for a workaround. Hope someone find something. :]

M.E.L.
02-20-2006, 11:12 PM
Just outta curiosity why would you want a RP on a single chain with a pole vector?

Essentially the RP solver requires 3 joints (2 bones) if you wish to incorporate a poleVector. if you're using anything less than that then a SCSolver is generally the route to take for single chain operations (i.e. 1 bone).


-s

nullNode1
02-22-2006, 10:13 AM
hi. just butting in...
in eric miller's divine spine, those rotate plane ik handles would allow you to rotate the spine in the axis facing the next chain. that is why he needs to place rp ikHandles on a two joints.

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02-22-2006, 10:13 AM
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