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View Full Version : Is this Gimbal Lock?

Trans-Delek
03-20-2009, 02:04 AM
So I've been animating a scene out, and I'm not sure what happened, but all of a sudden something I can't figure out happened with the rotation functionality on the rigs I am using (Max and MooM). I've seen this happen before, and it seems to come and go, but this time I am four days into this animation and this problem is making it extremely difficult for me to refine the animation and finish it out.

This feels difficult to explain, so I'm going to do the best I can. When the rig is in it's default pose, I can select the IK Wrist control and highlight "Rotate X/Y/Z" in the Channels Box and middle-mouse drag to rotate only that value.

However, if I try to do so again when the hand is posed doing, say, resting on a table, the rotations on the joint suddenly seem completely randomized. Indeed, Rotate X and Z are practically rotating the wrist in the exact same way! Clicking into null space, and reselecting the wrist control "resets" the rotation handle display, but if I click on any axis to isolate-select it and then rotate it, say if I click the Green "Y" curve, and then rotate it, the values for all three channels are changing.

I've opened ever rig I have on my computer and they all seem to be doing this, with every rotating joint they have. Did I inadvertantly tell Maya to do something different to cause this? This is making it almost impossible for me to animate, and the thing that's really driving me crazy is that I don't have any idea what to do, or if this is just the normal way these things function?
DruG
03-20-2009, 06:27 PM
If you`re rotating in Local space then it`s normal. Changin to Gimbal allows you to animate in all channels seperately.

Look into Tool Options with Rotate Tool selected. Or hold Rotate button and then hold Left Mouse Button.
MolemanSD7
03-20-2009, 06:59 PM
It sounds like that's what you're fighting. Also, if you're not animating in Gimbal mode, then as you change the rotation of the controller, its compensating to hit the pose you want. So, the final frame is what you're looking for. However, when it plays back, depending on the rotation order (that is if it rotates in X then Y then Z or something else) the results can be odd. If you animate in Gimbal you'll see exactly what your controls are doing.

I would suggest doing that, and then looking to change the rotation order if necessary. In Maya, if you set the rotation order to XYZ it will rotate on Z first, then Y, then X. Its backwards I know, but that's how it goes. So, you would want Z to be the main axis the control is always going to move on. Y, the second most common, and finally X is the least common (usually a twist or rotate axis). That, at least is how the XYZ rotation order would behave.
Trans-Delek
03-21-2009, 11:46 PM
Thanks for the info. The most baffling thing is that I don't know if it's always been like this and it's taken me this long to notice, or if I've really managed to screw something up.

I guess I always figured that the rotations, like say on the head, would stay fixed to their original orientation. Like, the rotate-X value will always run on a sagittal plane around the head, and positive value would rotate the head up towards the eyes and negative value down in the direction of the chin. Instead, it seems locked to the orientation of the head to the rigs Root.

This really makes it hard for me to put in subtle movements, like a short, downward flick of the finger and wrist to de-ash a cigarette. At first I noticed the problem was largely because the rotation values were in excess of 220+ each, and when I grabbed all the keys in the graph editor and brought them back towards 0, they moved with signifigantly less unintended rotation. But I can't completely get rid of it. It sucks.

And when I rotate the IK wrist control to a certain degree, like say on the Y-axis, to the point where X and Z are pretty much synonymous, I have to completely rethink a pose because it's going to be so tough to just get any intended movement.

So you say I should try animating in Gimble so I at least know what the rotation axis' are doing? I'll give that a shot, thanks for the tip.
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