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fixed local axes?

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Tilmann Schneider
fixed local axes?
on Apr 4, 2011 at 12:44:21 am

Hello,

I wonder if there is any way of having the local axes of a 3d layer fixed?

I want to rotate e.g. the x-axis without having the y and z-axis point in ever changing directions.
At the moment when I change the rotation value of two axes at the same time not only the layer rotates but also the axes around which the layer rotates rotate. And that gives an pretty uncontrolled rotation in the end.
I tried the world axis mode but it turned out to be just a translation for the rotation tool.
I need the axes fixed because I parented the values.

Just for a better understanding, here is my practical problem:

I created a 3d sphere in photoshop, imported it and now I want it to roll over a piece of paper, camera from the top.
I parented the x-rotation to the y-position and the y-rotation to the x-position.
So far so good. It works as long as I move the sphere only in one direction (x or y). When I start to move it diagonally or in a curve the sphere starts to skid and twirl uncontrolled.
This is because the axes around which the sphere rotates rotate as well.
To have them fixed would solve my problem.

But I'd be happy about any solutions to this problem.

Any ideas anyone?

Tilmann


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Tudor "Ted" Jelescu
Re: fixed local axes?
on Apr 4, 2011 at 6:31:43 am

It was getting really difficult to explain, so I just made a test project - instead of a sphere I made two intersecting 3d layers, but the principle should be the same. Let me know if it works.
1832_spherecontrols.aep.zip

Tudor "Ted" Jelescu
Senior VFX Artist


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Tilmann Schneider
Re: fixed local axes?
on Apr 4, 2011 at 11:36:09 pm

Hi Ted,

Thanks.

Which layer do I need to move in order to move and roll the sphere (the one made of two shapes)?
I haven't quite figured that out yet in the composition.

I need to be able to create a position path.

Cheers

Tilmann


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Tudor "Ted" Jelescu
Re: fixed local axes?
on Apr 5, 2011 at 10:32:58 am

I won't get to my machine till late (production shoot). I think in order to follow a path you may need one more Null, but I'll have to test this later on.

Tudor "Ted" Jelescu
Senior VFX Artist


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Tudor "Ted" Jelescu
Re: fixed local axes?
on Apr 6, 2011 at 1:53:06 pm

Here's a more refined version of the previous project. The first one was just the rough idea, it needed some work.
In this project you can link the MasterNull to a path and it should work. I left the Y axis simple, with no rotation to it.
Let me know if it works for you.

2159_spherecontrols2.aep.zip

Tudor "Ted" Jelescu
Senior VFX Artist


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Tudor "Ted" Jelescu
Re: fixed local axes?
on Apr 6, 2011 at 8:10:25 pm

I did some more tests and it seems it still has the same issues- basically you need an expression that will compensate on each axis for the rotation that happens on the other axis. Since I am not really an expressions master, I was not able to figure it out, but was worth giving it a shot- at least it gave me a great idea for setting up a rig for animating tires in AE. Post a question on the expressions forum, if you did not already, and you may find an answer there.

Tudor "Ted" Jelescu
Senior VFX Artist


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