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Using rotation null on moving characters

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Tim BentleyUsing rotation null on moving characters
by on Mar 24, 2013 at 6:39:25 pm

Can anyone help with a parenting question - I have two (3D) animated characters, with thousands of keyframes for position, rotation and anchor point already set. At a particular moment, the two characters are side by side, and I want them to rotate around a single point (quite far from their positions).

Normally I would parent them both to a null and rotate it, but I cannot do this without creating big problems with the rest of the animation. Is there any way of doing this without changing the anchor point so it is the same for each during the rotation, then snapping it back to its next position? I really don't want to do this as simply by adding the keyframes to change the position / anchor point it interferes with the motion of the characters.

I know this is technically possible using the pan behind tool, but I really need to do it without adding the extra keyframes that involves. Expressions, maybe?

Can post screenshots if it's not clear! Thank you!


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Tudor "Ted" JelescuRe: Using rotation null on moving characters
by on Mar 24, 2013 at 7:40:04 pm

Screen shots would help- at this point it is unclear to me at least why you can't use a Null to parent the two and rotate

Tudor "Ted" Jelescu
Senior VFX Artist


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Roland R. KahlenbergRe: Using rotation null on moving characters
by on Mar 25, 2013 at 12:20:54 am

1) Split the layers at the point in time where this rotation is supposed to happen.

2) Parent the affected layers to a strategically placed Null.

3) Commit to the rotation.

If you need to remove the Parenting, split the layers again and remove the Parenting.

As always, be mindful where the Timeline Indicator is when you Parent/unParent. Always check that the Parenting structure does what you want - there is always the Undo feature to get you back if you slip up.

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects ACE/ACI (version 7)


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Tim BentleyRe: Using rotation null on moving characters
by on Mar 25, 2013 at 10:28:57 am

Thank you for your advice - in the end I did almost exactly that, except I duplicated the character layers rather than split them (they themselves are parents to 20+ other layers, so couldn't be split) then did a single frame opacity change, with the two duplicated layers parented to the null as you describe. I linked the motion of the null to the originals, adjusted the anchor point and rotated it. It wasn't quite so simple, as this screwed up a couple of expressions I had, but it was just a question of finding what expressions to remove / change from the duplicates, and most expression-based values I re-linked to the original layers.

Ted - there were several reasons for not wanting to parent the characters to a null - they already have a parenting structure which is quite complicated, and by adding a further parent I got unwanted rotation in the intermediary children / parents. It also interfered with some expressions, as I describe, and the fact that both characters are in (uneven) 3D motion didn't help. Basically I could have just linked them to a null, but it would have created more problems than it solved - hence the question :-)


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Tudor "Ted" JelescuRe: Using rotation null on moving characters
by on Mar 25, 2013 at 10:42:33 am

I can understand that now with more details - I think it best to throw in as much info as you can from the beginning. This helps get more options and faster answers.
Splitting or duplicating layers would have been my choice as well.

Tudor "Ted" Jelescu
Senior VFX Artist


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Roland R. KahlenbergRe: Using rotation null on moving characters
by on Mar 25, 2013 at 10:43:52 am

Thanks for reporting back Tim. Do you think adding another camera that was parented to a Null would achieve the same trick and with less mucking about with the layers?

Cheers
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects ACE/ACI (version 7)


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Tim BentleyRe: Using rotation null on moving characters
by on Mar 25, 2013 at 11:10:11 am

Ted - yes, 'creating big problems' was a bit vague - I was tired and being lazy ;-)

Roland - unfortunately there are numerous background elements as well, otherwise this would have worked. One other possibility which I considered was pre-comping the two layers together and rotating the pre-comp - again not possible in this case because of the render order, but would definitely work for a simpler composition. I've run into a few problems recently which are caused more by the complexity of the composition (700+ elements, lots of expressions and tens of thousands of keyframes) than by any particular AE issue. Often the solution which requires the fewest global changes to implement is the best!

The idea of an expression (or effect) which creates an autonomous "rotation + anchor point" parameter was what haunted my dreams last night, but in the cold light of day I know that a parented null does just that, and I've never run into the need for an alternative before - and, as I say, it would technically have been possible, but given the stage of the project it was difficult to add without creating unwanted after-effects (no pun intended).

Thanks for all your help!


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