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Transform a 3D motion path

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Xavier Gomez
Transform a 3D motion path
on Nov 27, 2012 at 11:53:38 pm

Hello, there are few old posts on that topic but i'd like to check for new advices.
By transform a motion path i mean translate/scale/rotate, not arbitrary transformation.

Basically a 3D-layer already has a keyframed position, the motion path is globally satisfying but i would like to transform it, for instance (it's the case i'm at but it doesnt need to be so) to make transformed copies of the path for other layers.
The method i use is the one i think is the most widely used:
parent the 3D-layer (the one carrying the motion path to be modified) to a 3D-Null, cancel out any offset in the "Transform" group (except opacity obviously) using straightforward expressions, then close that layer and manipulate only the null.

The null doesn't need to be keyframed, it just takes constant offset values to change the child's motion path as a whole.

The thing is that to see the result of changes made in the null's properties, i need to see the motion path of the child layer, hence select it. But if the layer is selected along with the null, changing the null's values adds key frames to the corresponding properties of the child layer, which i don't want. Locking the main layer doesnt work since it not only prevents editing it but also selecting it ...

So what i (feel forced to) do is to make some guess change in the null's properties, select the layer et see the changes, deselect it, reajust the null, reselect the layer to see the changes, deselect and so on... super annoying.

there is another possiblity : get rid of the parenting, write all the corresponding affine transformation by hand in the position expression of the layer, and activate the post expression graph. It works but it is super slow (because of the post expression graph with a long expression), while parenting gives instant result.

It would be a lot simpler if the was a possiblity to see a motion path without selecting the corresponding layer (for instance a button on the timeline, or allow locked layers to be selected).

But if someone has a different (working...) approach to do that kind of things, please share.

Xavier


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Darby Edelen
Re: Transform a 3D motion path
on Nov 28, 2012 at 2:29:39 am

Just tested in CS6 and with a parent and child selected you can move the parent without adding keyframes to the child.

Are you using a version earlier than CS6? Perhaps it was added in that release.

Darby Edelen


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Xavier Gomez
Re: Transform a 3D motion path
on Nov 28, 2012 at 10:50:38 am

I'm using CS5.5, but i'm surprised you can do that in cs6. How do you do that ?

Usually when several layers are selected (child parent or not), changing a Transform property of one changes the corresponding Transform property of all at once. (If the change is made by entering a value using the keyboard, all layers are given the same value, and if the change is made by scrolling, they are all offset by the same value).
It's a nice feature for group move, but in the situation i describe above it's not, since one needs to select the child layer to monitor the changes of its motion path, but dont want to add keys.

Xavier


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Darby Edelen
Re: Transform a 3D motion path
on Nov 28, 2012 at 9:41:27 pm

[Xavier Gomez] "If the change is made by entering a value using the keyboard, all layers are given the same value, and if the change is made by scrolling, they are all offset by the same value"

Ah, that's the problem. I was using the composition viewer to transform the parent object. Try manipulating your parent null's axes in the composition viewer.

Just did this in CS5 and can confirm that it works.

Darby Edelen


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Xavier Gomez
Re: Transform a 3D motion path
on Nov 28, 2012 at 10:30:42 pm

hmm, answer much appreciated!!! Glad that i asked.

I was feeling uncomfortable with those axis manipulations so i'd almost never use them...(!)

Thank you,
Xavier

(beside this, i still have the feeling that it requires a lot of preparation work to be able to transform a 3D motion path in AE, and really, it could be improved).


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