PDA

View Full Version : Gimbal or local rotations, which to use?


Mithrandir315
02-06-2006, 06:10 AM
First of all, I'm writing this post thinking specifically of Maya. I'm posting it here though because I think everybody runs into these problems, no matter what package they use.

I'm wondering what kind of rotation most of you animators use. I really don't like using quaternion (TCB) rotations because of the lack of f-curves. So with using Euler rotations, what kind of rotations do you use? I mean, world, local or gimbal. I usually used local to avoid the risk of gimbal lock. But when adjusting my animation curves, I found that they were following the gimbal rotation anyway. So my main question is, do you animators animate with gimbal rotation? And is there any advantage to animating with local rotations, since the software 'thinks' in gimbal anyway? Then, if yes for animating with gimbal, what is the best way to avoid gimbal lock, or minimize running into it? Righto, well any input would be much appreciated!!

eek
02-06-2006, 10:15 AM
I thought displaying 'gimbal' is just a graphical representation local rotation, but will also show you when gimbal lock starts occuring. Therefore prempting you to rotate out of it. With euler rotations your'll always get gimbal occuring in some way, quaternions you wont because each axis isnt caluated seperately but rather all in one big equation, that cant be seperated. Good rigging, seperation of axis', correct parenting will minimize gimbal but never remove it for good. As with matrix transformation, scale is really a side affect of rotation where as position is really a seperate system, sheering occurs as a result of normalize vectors of a matrix being in the wrong postion etc. Scale is a result of the vector length from the origin. Basically if you have 3 points in space, and draw a line to each from the origin, this is you axis. If the length to each point is 1, this is a scale of 100%, also if these axis are at 90 degrees to each other then the transformation is correct otherwise odd things happen.

So until some math genuis devises a new way of working out rotations, where stuck for the minute.

eek

Winner
02-06-2006, 09:12 PM
I usually just animate in local - if i get any gimbal weirdness I just apply the euler filter in the graph editor and that usually fixes any weird interpolation 100%... Ive done it this way for years, and never really run into gimbal as a problem.

Mithrandir315
02-07-2006, 12:38 AM
Hey guys, thanks a lot for the comments! Winner, what's this 'euler filter' you speak of? I don't think I've heard of that, could you explain more? Thanks again for the help.

Winner
02-07-2006, 03:09 PM
sure man ... you can find the euler filter in one of the menus of the graph editor ( sorry im not in front of maya right now and I cant remember which one ) ... theres no options just "euler filter"....

you select your curves ( or rather sets of keys ) in the graph editor that might be freaking out in your animation, and simply apply the euler filter. 99% of the time - dont ask me how the hell it does it - but maya does a really nice job of cleaning up the interpolation so its nearer to what you would expect, without the weird dips or twists that come because of gimbal lock

eek
02-07-2006, 04:52 PM
ooohhh ok, yes. This im guessing looks at the keys and normalizes them.


eek

Mithrandir315
02-07-2006, 10:10 PM
Cool, thanks guys, I'll check that out!!

CGTalk Moderation
02-07-2006, 10:10 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.