(edit: solved. I placed a solid in an area where I did have tracking points, then resized the solid so that its edge touched the horizon. In AE side view, I placed the city on top of the edge of the solid, i.e. where the horizon is. Works nicely.)
I'm tasked with placing a city silhouette in the horizon of a shot. The shot is aerial, first looking at a person from nearly directly above. The camera moves back and up, finally tilting up to reveal the horizon in the distance (see attachements).
I did a 3D Camera track in After Effects, and the track itself is fine: I'm able to place 3D elements in the scene and they stay put. However, I have no track points near the horizon or on the sky, so I can't know how far away in 3D space the spot is where the city should be. If I place a 3D element in the scene and move it further from the camera to the distance approximately where I think the city should be, the element will not stay in it's place but moves in a somewhat random looking movement.
Any help with how to place an element in the distance near the horizon so that it moves and scales correctly would be very much appreciated! Thanks.