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I'm running into an odd problem in After Effects (I'm currently running 4.0 but I've seen it in other versions as well); I'm getting interpolation based on previous values in hand-keyframed sequences.

For instance: If I set two keyframes and use them to move an object from point a to point b, After Effects interpolates the steps in between (as it should; so far, all is well). If, however, I add a third keyframe between the two original ones and change it to a different position (point c, which lies between point a and b) the interpolation between point a and point c uses the old interpolation*(i.e., it jumps forward and then back to point c). In this particular case I'm simulating the movement of a table that's being moved by a user on-screen; it's not a nice smooth movement but typical human-being movements with pauses, jerkiness, etc. so I want to be able to change the scrolling speed to match the original table's movement.

Is there a way to re-set the interpolation between points (or have it re-interpolate)? Generally I've found that AfterEffects will re-interpolate as I add points but occasionally run into this and I wanted to know if I'm missing something basic. For now the fix is to go back and add keyframes manually for every point in between the two problem children, which is a pain.

  • Can you upload a image/gif for this issue? – p2or Dec 17 '14 at 16:08
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Select both of the keyframes, Then Control-click on one of the keyframes, then select "Keyframe Interpolation..."

A menu box will pop up that allows you to control the interpolation between the selected keyframes.

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It's a bit hard to tell, but this sounds very much like the behavior you would see if the CTI were just slightly off the keyframe when you repositioned the object.

When you're inserting keyframes and manipulating them, it's a really good idea (I say this having learned it the hard way!) to use Next Keyframe and Previous Keyframe to position the CTI, to ensure you're really manipulating what you think you are.

Another possible fix would be to edit the motion graph and/or delete and reapply whatever easing you're using. I've not run into this issue, but it could be that Ae just needs an extra prod to understand what the transitions are in some edge cases like this.

  • It shouldn't be - when I add the "third" keyframe (really the second one since it's in the middle of the two original ones) I let AE create the keyframe automatically. – lawndartcatcher Dec 19 '14 at 21:03
  • That will create confusion, though. You really can't split a transition like that with auto-keyframing, much as it seems logical. Create the keyframe, establish the easing, then make the positional/path changes. – Alan Gilbertson Dec 24 '14 at 4:56

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