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  • Strange movement between 2 static keyframes

    Posted by Ken Evans on November 2, 2011 at 5:04 pm

    I have 4 keyframes in a very basic move on a comp.

    KF 1 moves the item onto the screen. KF 2 stops it. KF 3 tells it to move again and KF 4 stops it again.

    However between KF’s 2 and 3 although there is no difference between them, there is a strange to and fro movement on the item. If I grab the bezier handles and twist the path it shows there is a little loop there and the item dances around it during the paused section where it shouldn’t move.

    I can’t seem to get rid of it and I had this problem before and forgot how to solve it.

    Any ideas what this is????

    Matt Bacon replied 6 years, 1 month ago 5 Members · 6 Replies
  • 6 Replies
  • Michael Szalapski

    November 2, 2011 at 5:25 pm

    It’s called the boomerang effect and is talked about here: [link]
    It even includes a link to a couple of Creative COW tutorials about it.

    – The Great Szalam
    (The ‘Great’ stands for ‘Not So Great, in fact, Extremely Humble’)

    No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

  • Roland R. kahlenberg

    November 2, 2011 at 6:24 pm

    The solution is to set the first of the ‘repeat’ keyframe to a Hold KF. More folks should how and when to use it.

    Aharon Rabinowitz provides a pair of video tutorials on the Creative COW website that describe the issue and solution for the boomerang motion problem that arises from unintentionally having Auto Bezier spatial interpolation set for keyframes of equal value:

    The above quote is taken from the Adobe link by Michael. The text I have underlined is to highlight the issue on hand. The boomerang effect can also come about from any non-linear Spatial Interpolation. IOW, the boomerang effect is not restricted to having Spatial Auto Bezier keyframes.

    Lots of folks do not appreciate how the boomerang effect is created. Unfortunately, Aaron didn’t touch on this in both of his tutorials. It’s fine knowing the solution to a problem but it’s better to know its cause. For now, just take note that the boomerang effect is NOT caused by an anomaly in AE but by user-error.

    Hopefully, I can find some time to do a tutorial. For now, should you want to Hold on to a position, ensure that you use a Hold keyframe.

    HTH
    RoRK

    Intensive AE & Mocha Training in Singapore and Malaysia
    Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer

  • Ben G unguren

    November 3, 2011 at 4:09 am

    FWIW, there is an AE preference to “default spacial interpolation to linear” keyframes (off by default). I prefer to turn this on, and then bezier things up on my own after roughing out the initial animation. I find I have fewer unexpected results this way.

    Really, this should be the default pref in AE, as default bezier throws less-experienced users off pretty frequently. But I suppose it’s been the other way for so long, it would disorient a lot of experienced users if suddenly the pref changed…

    Ben Unguren
    Motion Graphics & Editing
    http://www.mostlydocumentary.com

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  • Roland R. kahlenberg

    November 3, 2011 at 6:48 am

    [ben g unguren] “FWIW, there is an AE preference to “default spacial interpolation to linear” keyframes (off by default). I prefer to turn this on, and then bezier things up on my own after roughing out the initial animation.”

    Very true Ben. Unfortunately, from having taught hundreds of AE users in a classroom environment, it’s inevitable that a Bezier-type Spatial Keyframe will be used in the course of one’s work. Then, we’re back to where we started.

    As long as folks apply a Hold Keyframe when they want to hold onto a property’s value, the boomerang effect is a non-issue.

    HTH
    RoRK

    Intensive AE & Mocha Training in Singapore and Malaysia
    Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer

  • Ken Evans

    November 3, 2011 at 10:15 am

    Thanks very much for all the very helpful answers.

    Now I understand exactly how this happened!

  • Matt Bacon

    March 27, 2020 at 6:09 pm

    Hello,

    Is there a way to make AE CC create hold keyframes by default?

    // I recognize this is an extremely old thread and I’ll probably also pose this question as a new post.

    Cheers,

    Matt

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