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View Full Version : Keyframe interpolation, transformation curves problem..

maiz777
08-05-2008, 02:02 PM
Hey,

I've been using AE for a while now but never actually understood how could I control transformation curves and it drives me crazy sometimes. AE is nice program but this thing just keeps me bothering.

Down here is a picture about the issue I often got when working translation curves and it happen when I want to make nice and smooth ease for translations. Like you can see from the upper picture that my curve between two linear keyframes is really weird and it gets even more weird when I convert those keys to spline. It should be straight line now from one keyframe to another but ae makes this weird jump there and that wold be my quiestion how could I control or prevent this kind of behaviour. I've tried everything, changeing interpolation (all possible combinations), changeing keyframe velocity and etc but with no luck and I always end up makeing compromises in my animation (for example if u bring keyframe up a bit then it goes away...bottom picture).
So I would be really thankful if somebody knows how to effectivly control translation curves in graph editor or some kind of workaround or something.

Tnx,
Maido

http://filmpost.ee/maido/RW/af_curves.gif
Mylenium
08-05-2008, 03:51 PM
Well, if it's not the infamous display errors, then it may be two keyframes in the same place. This can happen in NTSC comps with 29.97 or with time-remapping. It so happens, that you create a keyframe just a microsecond before your other one if you don't jump the keyframes using the J and K shortcut, but rather rely on the timeline indicator scrubbing... This is a known issue that hopefully finally in CS4 will get fixed.

Mylenium
mart1jn
08-05-2008, 04:21 PM
Hi,
I think I know why this happens but I hope I can explain this properly.

The way position keyframes work in After effect is a bit different than most other 3d programms I know (this also applies to 2d keyframes): In the Timeline/Graph window you can only edit the temporal information (speed) of the keyframes; in the Composition window you can only edit the spacial information (position).

Between keyframes the layer has to move a certain distance. Adjusting the speed at the 1st key will automatically adjust the speed towards the 2nd.
To make movement slower you can either increase the time between keyframes (in the timeline) or decrease the space between keyframes (in the Composition window)

This seems very obvious, but it means that if you have a reasonable amount of distance to cross and ony a few frames, you will never get a nice ease out animation.

My guess is in your case you have to decrease the distance between the keys in space or add a few frames.

I hope I got the problem right and the explaination clear :D
Cheers
Martijn
maiz777
08-07-2008, 03:59 PM
Tnx mart1jn, you where right, I was able to fix that thing from composition window and that is exactly what I have been looking for :) I tied to find a way to change keys slopes from graph editor but in AE you can do it from comp widow. It still quite weird solution but better than nothing.

So tnx again.
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08-07-2008, 03:59 PM
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