animating rotations: newb question

[simmsimaging]

I do only stills work so know almost nothing about animating in Max. I have a grip on a few basics, but they are failing me badly right now.

I'm trying to create a rotating cylinder to generate some motion blur (spinning on it's vertical/z-axis so the end looks like a spinning wheel). I set a keyframe at 0 and then rotate along z at frame 20, and scrubbing shows a smooth rotation.

However if I need the cylinder off perfect alignment to world origin then the exact same rotation creates a bizarre wobbling motion. I can't figure out how to get an object that is off-axis to the world to rotate smoothly around only one of it's own local axis.

Seems like it should be simple - am I missing something obvious or is this actually hard to do in Max?

Thanks for any help.
b

[add101]

Do you mean you moved the object from the origin, or you you moved the axis pivot (using Heirarchy>pivot)?
Why do you want to have object axis modified? This would create an irregular animation.
posting a picture might help...

When rotating the object- are you using 'Local' for the reference co-ordinate system? (next to the rotate button on main toolbar)

[SnipeyX]

Other things to look into: The axis rotation order: Command Panel > Motion tab > Select the rotation button under the PRS Parameters Rollout then look in the Euler Parameters Rollout and change the Axis Order from the dropdown menu.

Alternatively (and perhaps easier) would be to link the object to a dummy or point helper, then rotate the helper object off-axis.

[simmsimaging]

Thanks for the help!

No, I wasn't looking to move the pivot, just the object. I just found that if the object stayed aligned to world coordinates then the rotation worked fine, but if the objects was moved around then the 'local' rotation got screwed up when animated. I can rotate it properly in the viewport, but the playback is messed up. I recorded a screen cap to show how the object wobbles after- hopefully this is clear. In the vid the wobble is fairly minor, but still a problem.

http://screencast.com/t/NTc5OGIy

How do I avoid that?
THanks again!

[simmsimaging]

Following SnipeyX's advice, we tried changing the XYZ orientation prior to rotating and that seems to have done the trick. Just had to choose the combination that *started* with the rotation axis we were trying to use.

Maybe it's just me, but isn't that a bit of PITA for a simple animation requirement? What do I know though?

Thanks for the help!

b

[jonahhawk]

http://www.guerrillacg.org/

There are some great "101" level explanations of many things CG on this site; including Euler rotations and gimbal lock, rotation order etc. This is a problem that is not only related to 3dsMax (for a change)

[simmsimaging]

Thanks, I will check out that link for sure.

b

[judderman]

http://www.cahal.net/simms.zip There's a max file hopefully demonstrating how to do it.

I created a file with a cylinder animated like you did, except it doesn't wobble

The way I achieved this is though using the motion panel to create keyframes and animate it around it's Y axis. You can see it in the zip file. I also made sure the pivot point was in the centre, which it should be if you create it from a primitive.

[simmsimaging]

This seems very simple - thanks very much for taking the time to put that together. It's a big help!

b

[judderman]

No worries, good luck with it!