I don't have the opportunity to use cameras and 3D movement very often, so I feel like a perpetual newbie when I do. I could swear I'm doing this right, but the result isn't what I'm shooting for. A little help, all?
I've built a 3D television set and nested the comp into another where I've set up a camera. I've placed a 1x1 3D null in the center of the TV to serve as the Point of Interest.
However, when I activate the expression for POI on the camera and use the pick whip to select the position of the null, the result is that the TV ends up skewed way off center - halfway off screen, up and to the left.
What am I missing?
I wouldn't precompose the TV layers.
Leave them in the same comp as the null and parent them to the null. If your sequences get too hairy then you can make them shy and hide them.
I'm not sure what type of camera move you want to accomplish. If you want a camera that will fly around the TV then duplicate the null in the center of the TV. place the camera in its starting location and make it a child of the new null. Animate the position and the rotation of the null and the camera will follow.
If you want the camera to always look at the front of the TV then place the camera at the correct location then make it a child of the original null. as you animate the null then the TV and camera should move together.
I don't think you need the expression in either case unless there is something else you want the camera to do.
If the null is parented to the TV then its position property will be relative to the TV instead of the world coordinates. You would need to translate the Null's position into world coordinates like so:
l = thisComp.layer("Null");
Darby Edelen Designer Left Coast Digital Santa Cruz, CA