convert 1-point camera to 2-point camera with expressions?

[Ryan Hill]

Trigonometry. I believe there are sin cos and tan functions available.

This covers some related subject matters:
https://www.creativecow.net/show.php?page=/articles/ebberts_dan/particle_gen/index.html

[Pshpsh]

If anyone knows specifically what I need to use. If I tried to figure it out, it would be pure guesswork. This stuff boggles my mind, seriously. I know Dan can do this in his sleep…

[Ryan Hill]

You know the X, Y, and Z location of the camera, and the angles it’s pointing. You want to calculate the location of the point of interest.

Just to get one thing out of the way; there is no one single answer as to where the point of interest will be. It can be anywhere along a line pointing away from the camera. So, you’re going to have to assign a distance arbitrarily, to get a single point.

What exactly do you plan to do with this point once you have it?

[Pshpsh]

Well, the plan was to export that keyframe data and import it into Cinema4d. So then I could create a 3d object and export it back to AE. The XYZ rotation keyframes weren’t translating very well into C4d, but POI cameras were.
I’m trying out some different solutions now. I’ve talked to a few people about this and it seems pretty hard to do in AE. Thanks for your help though.

[Ryan Hill]

So if the distance doesn’t much matter, then you can assume the hypoteneuse is 1, making the math a little simpler.

Something like:

[position[0]+Math.sin(rotationY),
position[1]+Math.sin(rotationZ),
position[2]+Math.sin(rotationX)]

I might have X Y and Z backwards, but it makes sense to me. And you’ll want to pick-whip to get the real attributes of your camera.

Also, you might be able to avoid expressions by parenting a null layer to the camera, with the anchor right on the camera, and the position right at where you want the point of interest. But I can’t test any of this right now, because I’m not at a computer that has AE.

[Pshpsh]

Thanks for responding RobotHero.

That looks like it should technically work, but I haven’t got it to yet. I’ll keep trying…