[Michael Reisinger]

Ok, thanks to Jeff’s guidance I’ve figured out how to transform AE’s 3D Camera Tracker into an object tracker. It requires a bit of work, and if you have another application on hand it’s probably a better solution. Here’s what I did:

1. Apply 3D Camera Tracker to your footage.
2. Select track points and create Null + Camera
3. Mute the newly created camera
4. Apply this expression to the null’s orientation property:

lookAt(NULL POSITION, CAMERA POSITION)

5. Apply Track Motion (yeah, I know … 2 tracking solutions involved) to your footage. Use a Track Point in the area where you want to track in your 3D (in my case C4D-based) object.
6. Apply an expression linking your null’s position to the Track Point’s Attach Point.
7. At the initial frame of your track, calculate the delta between the null’s position and the camera’s position.
8. Apply an expression to the keyframed camera position property, subtracting the delta value from each coordinate [x-dx, y-dy, z-dz]
9. Your null now MOVES!
10. You’ll have to reposition the null in both AE (no big deal since the camera now automatically moves to the right spot due to the camera position expression) and in C4D (simply parent your moving null to a new null and reposition as necessary).

This worked for now, but there has to be a simpler, more elegant way to do this. I’m all ears …

[Michael Reisinger]

Aha, thanks Jeff – I will try the expression approach ASAP. But, just to be clear …

The results from 3D Camera Tracker do not include a moving null, only a moving camera. When I bring the 3D Camera Tracker data into C4D, I get a stationary null and a moving camera. I want a moving null. Possible?