I have a composition with some 3d primitives (done with 2d layers) that are precomped and with "collapse transformation" activated. I have 12 cameras for the different angles, I turn camera layers on and off to do a sort of "editing" of my scene. Each camera is controlled by a parented null object (one for each camera). The 3d elements (floor and objects) doesn't move, only the camera is moving.
I put a solid with trapcode particular between the 3d objects adjusting the emitter "position" parameters to position it in the 3d space. Problem is, it doesn't follow the camera movement as the other objects do.
If I manually correct the position of the emitter in a shot, when next camera is activated the angle and position of particular is all different.
Also, it looks as it is always in front, when instead it is supposed to be hidden by objects that are closer to the camera (or not?).
I have tried to parent the xy and z with expressions to a 3d null object but it does the same, it behaves different than other objects in the 3d set.
I really like to know how to make this particular layer part of my 3d "set" and stay in place so I can move only the camera over everything.
Thanks Ted, I was aware of that, it didn't mean between layers (it's on the bottom) but the position between objects (in scene). In the end, I did it parenting the xyz position of emitter to an existing object and now it is attached to the same position when camera is moving. For visibility, I set the objects in front as obscuration layers in particular.