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2D position from 3D layer wraps around behind camera?

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R. Zane Rutledge
2D position from 3D layer wraps around behind camera?
on Jun 10, 2020 at 9:50:01 pm

So I'm using the ever-useful

l = thisComp.layer("3D Null");
l.toComp(l.anchorPoint);

in the position of my 2D nulls to have a series of 2D nulls "track" 3D nulls in a scene. (Building a 2D spline that in screenspace mimics a 3D spline through space.)

Unfortunately, if my 3D nulls go "behind" my camera far enough, the 2D calculations suddenly seem to "flip" to the other side of the world. They're off-screen, but on the wrong side. I suspect maybe the numeric precision is wrapping off the end of the world space or something (?). Because these are points in a continuous spline that I'm feeding to another plugin (Boa), rather than that part of the spline just remaining comfortably off-screen, it suddenly crosses straight across the screen. (Say the spline was vanishing off screen over our POV "shoulder" in the lower left corner, now that 2D point is suddenly very far in the upper right, meaning the spline erroneously streaks diagonally across the frame.)

Wondering if there's some suggestion on how to keep the off-screen 2D nulls (or 3D nulls) in the right space off-screen or how to adjust the calculations when they go drastically behind the camera in Z space? (Perhaps some way to tell if they are behind the camera and then adjust to keep them closer but just off screen in the correct direction?)

Frankly, this feels like a job for Dan Ebberts. I just can't quite figure out the best way to tackle this.

Thanks in advance,
zane


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Richard Garabedain
Re: 2D position from 3D layer wraps around behind camera?
on Jun 11, 2020 at 6:15:50 pm

what is the auto orientation of your camera?


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R. Zane Rutledge
Re: 2D position from 3D layer wraps around behind camera?
on Jun 11, 2020 at 7:42:57 pm

Off. The camera is moving and keyframed. Mostly traveling in Z such that the various 3D points of the spline move from in front of camera to behind us (over the left shoulder). Think of it like a ribbon in 3D space. But for some reason, even though the first point has disappeared over my left shoulder low in frame, as it gets further and further behind camera, the 2D point suddenly is being evaluated as in the upper right corner instead of the lower left. Like maybe it "wrapped around" or something. It isn't actually traveling to the right, it just gets so far left that somehow the math is incorrectly making it positive again in X. Or something.


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