origin and ground plane (camera tracker)

Ive been working with the camera tracker for about a week now and read the manual but Im still confused about a couple things...


When setting the ground plane, should I be setting the ground plane of the 3d object I'm going to be placing in the scene or the actual ground (and what if the ground isn't in the shot?) Example - if I am sitting at the desk and the POV is a go pro on my head looking at my screen, should I set the desk as the ground plane?

Also, when selecting the Origin, is that for specifically lining up the 3d object into the scene where you want it placed right? And thats also the tracking point for that 3d object to be attached to? Is selecting an origin necessary or can I just move the object in 3d space as long as the ground plane is set?
Does the origin point have to the on the ground plane or anywhere in the shot?

Whatever works best for you, you should do. If you want to put something on a table, but not the actual ground, by all means make the table your ground plane.

So pick whatever helps you to get your shot done.

Ground plane and origin set the coordinate system of your solved scene. But coordinate system is not absolute, it is always relative. So as Sander wrote, set it up so it helps you achieve what you want. Origin is just the center of your coordinate system, nothing more. You can center it on some arbitrary object, to some very specific location, totally random etc, technically it makes no difference for solver.

So the origin point doesn't really matter? Or should the origin point be the center of the shot?

basically just set the ground plane and then move the 3d object around in the scene using the transform 3d?

Ive done so many solves and trials and errors and I can't seem to come to a conclusion. lol

Also, should I click un aligned, set the origin and ground plane and then pick aligned again after i set the two? or should i keep it un aligned after selecting?