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Forums Adobe After Effects Expressions Using the Smooth Expression with the 3D Camera Tracker

  • Using the Smooth Expression with the 3D Camera Tracker

  • Spencer Maxwell

    October 13, 2021 at 7:47 pm

    Hey everyone,

    I’m trying to solve a track with the 3D camera tracker.

    Whereas it’s pretty solid through the clip, there’s small bits with jitter because the software

    didn’t get it correctly. When I put in objects/replace the background with 3d elements they

    will jitter when this takes place.

    I wondered if I could fix this by using the smooth expression on the camera keyframes after

    the track, but for some reason this expression messes up the camera’s angle.

    It will randomly spin around when I apply this expression and I’m guessing it has something

    to do with the orientation property.

    The funny thing is, if I apply this same logic to 3d nulls but use the x/y/z rotate values instead of the orientation values it works fine. There’s something about the “orientation” parameter that doesn’t like this expression. When I’m animating in a fully cg workspace my solution is to make a bunch of 3d nulls and parent my camera to them, then animate the x/y/z values of these nulls to move my camera, after which smoothing these values. However, when I’m analyzing shots with the camera tracker it applies the rotation values to the orientation of the camera instead of the x/y/z rotate.

    I found this previous post which seems similar to my problem but none of it is making sense to me –

    If there’s a workaround I’d really like to hear it, thanks!

    (Hey Dan Ebberts if you’re seeing this you probably know what to do 🙂 )

    Smooth expression

  • Filip Vandueren

    October 15, 2021 at 11:10 am

    I was about to comment that I once found a solution for that, but it is in the thread you link to.

    The built-in smooth method just takes the mean value of a load of samples, and when they are hovering around 0° in an 0-360 range, you get that 180° flip problem.

    In essence: instead of using the built-in smooth() method, we rolled our own, that takes into account that the average of 1° and 359° should be 0° and not 180°.

    Kalleheiki wrote one that shifts the problem 180°, and I offered a solution that should work for all angles.

    But again: it’s a totally separate expression, not using smooth() at all but getting the exact same result.

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