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Forums Adobe After Effects 3D Camera Tracking – How to turn off the rotation factor of the orientation?

  • 3D Camera Tracking – How to turn off the rotation factor of the orientation?

  • Tom Pickard

    April 27, 2021 at 10:58 am

    Hello Everyone. I am testing 3D Camera Tracking for simple pop up trim path & text graphics and I have come to a brick wall.

    1. I added a 3D Camera Tracker to my footage (which is a flat shot drifting down a coat)

    2. I then attached a solid to tracking markers on the white embroidered North Face logo

    3. I then made (pre-composed) the solid into a trim path line / dot / text

    4. The attachment and the movement is really nice and smooth but the graphics rotate with the footage slightly. I do not want any rotation at all, I want it to stay horizontal throughout the shot.

    5. I have looked at the 3D Camera Tracker properties and see that the orientation keyframes are constantly changing, which makes sense. But I just do want the rotation factor to change. I have tried removing all orientation keyframes but then the graphics detach for the tracking markers. How can I stop the rotation?

    Any help would be much appreciated:)

    Many thanks,

    Tom.

  • Blaise Douros

    April 28, 2021 at 7:52 pm

    There are a couple ways to solve this, and the easiest is to not use the 3D tracker–the Point Tracker is a much better tool for this. It’s hard to tell from just a frame grab, but if the motion warrants it, it’s sometimes a lot easier to track it in 2D for 2D graphic overlays.

    The other thing you could do is set up the 2D graphics to Orient To Camera, which you do by right-clicking the layer, selecting Transform > Auto-Orient… and then selecting Orient Towards Camera. This will ensure that the object, though still floating in 3D space, will always face the camera.

  • Tom Pickard

    April 29, 2021 at 5:07 pm

    Hello,

    Thank you very much for replying to this thread, much appreciated 🙂

    So I have tried using the Point Tracker tool but doing this, the text/graphic doesn’t feel anywhere near as smooth as the 3D Camera Tracker.

    I followed the ‘Orient To Camera’ method which is great, but this only locked the 3D axis, not the rotation.

    Is there a way to lock the rotation value of the orientation?

    Thanks,

    Tom.

  • Walter Soyka

    April 29, 2021 at 11:33 pm

    Apply this expression to your orientation property, and say thanks to Dan Ebberts:

    try{
    L = thisComp.activeCamera;
    u = fromWorldVec(L.toWorldVec([1,0,0]));
    v = fromWorldVec(L.toWorldVec([0,1,0]));
    w = normalize(fromWorldVec(L.toWorldVec([0,0,1])));
    sinb = clamp(w[0],-1,1);
    b = Math.asin(sinb);
    cosb = Math.cos(b);
    if (Math.abs(cosb) > .0005){
    c = -Math.atan2(v[0],u[0]);
    a = -Math.atan2(w[1],w[2]);
    }else{
    a = (sinb < 0 ? -1 : 1)*Math.atan2(u[1],v[1]);
    c = 0;
    }
    [radiansToDegrees(a),radiansToDegrees(b),radiansToDegrees(c)]
    }catch(err){
    value
    }
  • Tom Pickard

    April 30, 2021 at 8:33 am

    Thanks a lot Walter (Dan Ebberts)

    But after I applied this expression to the 3D Camera Tracker’s Orientation, the text graphic loses connection with the tracking point and is now crooked throughout the whole shot.

    What can I do to straighten it out and keep it fixed to the tracking point?

    Many thanks,

    Tom.

  • Blaise Douros

    April 30, 2021 at 7:20 pm

    I mean, basically, you want the text to stay locked in place to a specific feature without rotating or moving in 3D at all, the way it would behave if it was actually located in 3D space, being affected by the camera. That’s cookie-cutter Point Tracker 2D tracking material. If the text was actually floating above the jacket in 3D space, it would be changing its perspective and orientation as the 3D camera moved around–that’s the ONLY reason to use the 3D Camera Tracker for what you’re describing.

    I suppose you could go through the rigmarole of placing a Null in 3D space at the point you want it to attach, then making the text 2D, and applying a Layer Space Transform expression, but that’s a really convoluted way of doing what you can just do with the point tracker.

    What it really sounds like is that you need to get a better point track–a point track is just as smooth, if not smoother in many cases, as a 3D camera track, as long as you get good data. It’s not always a case of set it and go–sometimes you need to clean up little jumps in the tracking data by deleting a bouncy frame or two, or choose a better tracking point, or track a different feature while placing the attachment point someplace else. Contrast and sharp points and edges are really helpful for the point tracker. And then don’t forget the little things–enabling Motion Blur at the tail end really sells the motion in subtle ways.

    Try point tracking something like the “E” in Face, and setting the Attach Point near the lower right corner of the logo.

  • Tom Pickard

    May 1, 2021 at 12:30 pm

    Hello!

    Thank you very much for your help on this. You were right – it was the tracking point, I had selected an area which was just white, not near an edge, so after choosing the corner edge of the ‘E’ like you suggested it is nice and smooth 🙂

    Thanks again,

    Tom.

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