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Topics - dtrbc

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General Anim8or Forum / Help with correcting orientation problems
« on: April 30, 2009, 02:49:44 pm »
Hello all,

This is based on a question I initially posted in the .97d preview forum, thinking it was a bug, but have now learned it is just an intrinsic problem in 3D animation.

I've been using anim8or for a few years, since mid 2006, and have always had an issue when rotating and object that, at some points in its rotation the orientation values will shift off a fraction of a degree. Thanks to user RudySchnieder, I now know this is related to the phenomenon of gimbal lock. Now I'm asking for help on what I can do to get around it.

I often have to work with very long scenes, and often have a lot of rotation going on--my job requires me to animate planets with accurate axial tilts, and this seems to be where the worst problems occur. I used to animate with keyframes, but have lately been using controller scripts. With keyframes one can sort of correct for the problem, but I have found it can be a huge timesink going through and trying to correct every little spot where it goes off--not to mention it can consume a lot of time to make a planet spin around and around and around a dozen times with keyframes, so I started using controller scripts.

I am wondering what I can do to correct for the problem of the object wobbling a little bit at some points when using a controller script. Here's an example script I was using in a recent project, this script controlled my camera's orientation:

float $speed;
$speed = -2;
$orientation = RPYtoQuaternion(-1., 0., ($speed*time));

It encounters problems near frame 0 and every 5400 frames thereafter (the sequence I'm making is 10800 frames long, 30fps).

Would it be possible to add or modify anything to correct for this problem?

Thank you so much for any help and, if I may add, a big thanks to Steve for making anim8or. It's an incredible program.

Anim8or v0.98 Discussion Forum / Bug/Glitch - Orientation?
« on: April 29, 2009, 02:33:02 pm »
Hello, I hope this is the right part of the forum to post this in.

I've been using anim8or for a few years, since version .9, and I've always encountered this bug--including, most recently, in .97d.

When I make an object rotate, that is, change its orientation continually (either with a keyframe for each 90 or 120 degrees of the rotation, or with a controller script), at some point during the orbit the object will shift slightly off the prescribed course. This usually seems to happen near 90-degree intervals--sometimes at, say, 0 90 0 or 0 0 0 or 0 0 90 or 90 0 0, depending on the original orientation of the object--it's different depending on the original orientation, but pretty much seems to always happen at least once per rotation, always in the same spot. Over the course of about three or four frames the values will shift off by a small amount (a fraction of a degree), but enough to make an odd, noticeable wobble in the final render. When I used to do everything by keyframes I could sometimes force it to work right, but now that I use scripts, there's little I can do.

Has this been encountered before? Can anything be done about it?

Thank you so much! This problem aside, Anim8or is an amazing program and can do some amazing things!

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