ADOBE AFTER EFFECTS: Forum Expressions Tutorials Creative Cloud

Weird "ghost" keyframes...

COW Forums : Adobe After Effects

<< PREVIOUS   •   FAQ   •   VIEW ALL   •   PRINT   •   NEXT >>
Maxime MarquisWeird "ghost" keyframes...
by on Jan 12, 2010 at 3:52:22 pm

I'm animating a camera using a Null object with separate XYZ. Between two identical keyframes on X value (i.e. the value is the same on position A and B) , for no reasons, the value changes anyway. An example: X value at 10:00 is 0, x value at 10:16 is 0 but the value between the two key frame will change going from 0 to 5 and going back to 0.

And no, there are no other keyframes or expressions on the camera or any other layer that could explain the change.

It happens to me once in a while. The only way to arrange this is to erase all the keyframes of the problematic section, and the one following, and keyframing again.

Any ideas what's wrong?

AE CS4, DVCPRO HD 24p footage


Return to posts index

Wieger de LeurRe: Weird "ghost" keyframes...
by on Jan 12, 2010 at 4:07:04 pm

Hi Maxime,

This is probably an interpolation issue; change the first of the identical keys to a hold-keyframe and it will be solved.

Cheers,
Wieger


Return to posts index

Maxime MarquisRe: Weird "ghost" keyframes...
by on Jan 12, 2010 at 4:32:17 pm

Thanks, I'll try that.


Return to posts index


Maxime MarquisRe: Weird "ghost" keyframes...
by on Jan 12, 2010 at 4:34:58 pm

It works, thanks. I still don't know what causes it. Did I press the wrong button somewhere?


Return to posts index

Dave LaRondeRe: Weird "ghost" keyframes...
by on Jan 12, 2010 at 4:52:17 pm

[Maxime Marquis] "Did I press the wrong button somewhere?"

No, you're merely experiencing what former AE forum participant Aharon Rabinowitz refers to as the "Boomerang Effect" when using Bezier keyframes. Making a hold keyframe at the proper point is a good solution, and it's the way I would handle such stuff.

You don't have to abandon the use of Bezier keyframes, you just have to know how to work with them. Search the AE podcasts for Aharon's two installments on the Boomerang Effect and you'll be set.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


Return to posts index

Maxime MarquisRe: Weird "ghost" keyframes...
by on Jan 12, 2010 at 8:43:26 pm

Thanks Dave, I'll have a look.


Return to posts index


Christopher R. GreenRe: Weird "ghost" keyframes...
by on Jan 13, 2010 at 8:19:36 pm

[Maxime Marquis] "The only way to arrange this is to erase all the keyframes of the problematic section, and the one following, and keyframing again."

There is another issue with keyframes that I feel should be mentioned (and may or may not have anything to do with what you're describing).
Linear keyframes used to behave differently (sorry, I won't be able to give you exact version-specificity here). In the old days, when you made a linear (default) keyframe, you could rely on the motion to be perfectly, well, linear. Nowadays, you may find that sometimes there is some floating going on close to the keyframes, and that the motion has curves to it. This graphic shows you what linear keyframes look like when applied to a solid position:

This can be seen only when you have "Motion Paths" selected in the View Options. The solution below requires this also. When dealing with camera animation, you need to switch from "Active Camera" view to another view, like "Front" (or another camera).
My favorite way of dealing with this, when I want to be sure I have true linear movement (no curving, easing, etc.) is to do the following (Windows users, please excuse the mac-specific key command here; I'm sure you can work out the equivalent): Float your cursor over the keyframe in the Composition window, hold down Command-Option and notice the cursor changes to the bezier control/break tool. If you click on the keyframe, the bezier curves will 'break' and become perfectly linear.



Return to posts index

Christopher R. GreenRe: Weird "ghost" keyframes...
by on Jan 13, 2010 at 8:25:12 pm

[sorry; this was in error, and i cannot delete the post]


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]