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View Full Version : Arm rotation problem(Is this Gimbal lock?)


jdexforwords
05-18-2003, 09:15 PM
Hi, I posted this at Highend, too. I'm checking both of them. hope someone help me out.


I'm now trying to do my character's shoulder rigging based on the article on Cane-toad.com's briliant tutorial(http://www.cane-toad.com/tuteRig_Shoulder.htm).
Everything going well so far, but finally when I finish the rigging, joints are moving very weird.
When I rotate my controlShoulder joint, It's OK with 2 axis (Y and X). In the case of Z axis, it looks good when I DON'T rotate any other 2 axis at all. But Z rotation doesn't work well with other 2 rotation.
I know that tutorial said it's expected and you can fix it with changing joint's rotation order. I tried all of rotation order, but nothing of them works well.

I attach my MayaAscii file. If you have some time to spare, please look at and make me correct.

http://briefcase.yahoo.com/bc/jdexforwords/vwp2?.tok=bcx4ukRBXZyJ4KR9&.dir=/My+Documents&.dnm=shoulderRig.ma&.src=bc

or

http://us.f1.yahoofs.com/users/8ff1f1f4/bc/My+Documents/shoulderRig.ma?bcYBvx.Abe3h4KR9

MayaAscii file made by Maya 4.0.3

Matt Leishman
05-19-2003, 06:19 AM
i checked out your file and it seems that the best rotation order I can find for it is "yzx". And when you rotate, don't use the little default rotation gizmo, actually click on one of the rotation channels in the channel box and then use the new rotation gizmo that you get when you do that, its a little more reliable and true when it comes to controlling your "real" rotations. Hope this helps some.

jdexforwords
05-19-2003, 02:33 PM
Hi! thanks for your input sithwarlord.

Yes. "yzx" order looks well. But I'm still having trouble with my joint in vertical position pulling by the gravity. it looks some of original-joints are locked.
I like your suggestion sith. You mean Gimbal Rotation Tool, right? It looks cool but as I said before, something is still weird to me.

So far, "yzx" method is good enough when I pose my character although Original-joint is not controlled by Control-joint perfectly. But this problem is still annoying me. This operation is not comfortable for me. I want to clear away this problem.

Is this something like Gimbal lock? I cannot understand it correctly.
I have problem about twisting arm mesh. If there's one joint it occurs losing volume of original mesh. For solving this problem, this simple 3 joints way is good, I think. But Isn't this popular?

And another question. I'm planning to buy A|W DVD by Jason Schleifer (http://store.aliaswavefront.com/dr/v2/ec_MAIN.Entry10?V1=385100&PN=1&SP=10023&xid=41107&DSP=&CUR=840&PGRP=0&CACHE_ID=0) If I bought this, Could I get clear about my annoying Gimbal lock problem? Please tell me, anyone who buy already!

And thanks again! sithwarlord!

Matt Leishman
05-19-2003, 03:36 PM
I am familiar with both dvd's Jason Schliefer has put out through Alias Wavefront. The one you are referring to is his firrst one. In it he talks much more about Gimbal Lock, and the issues surrounding it. Indeed, you have stumbled upon the famous Gimbal Locking problem. And if I remember correctly, Jason even says that there is no real way to stop the Gimbal Lock from happening. There are ways of cleverly working around it and minimizing it as a problem, and he shows some examples on this dvd on how to work towards something like that.

Sorry I couldn't be more help man.

jdexforwords
05-21-2003, 12:40 PM
Hi thanks sith again.

My joints' problem was rotation order. When I read your post, I just changed original joint1's rotation order and get the weird result. But now I changed all of three joints' rotation order and works perfect! I noticed that in reading another post which I also posted at Highend. Here (http://www.highend3d.com/boards/showflat.php?Cat=1,2&Board=mayaanimation&Number=148514&page=1&view=collapsed&sb=5&o=&fpart=) it is for who interested in this problem and solution.

But as he write, I cannot completely escape from Gimbal lock hell. It looks like I need to learn more about Gimbal lock in MIT. :cool:

I think that's a good idea to buy Jason's DVD for my understanding about Gimbal lock. thanks sith your review and suggestion about rotation order helps me a lot. I'll try to buy that DVD right now.

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