virtual presentation canvas with four tracking points

[simonfischer]

Hey!

I am shooting a scene in presentation-like way, in which a digital canvas in the background is needed. It's shot outside in a business surrounding. The presentation canvas should appear next to the subject, kind a what Apple does with their keynotes (although we don't have a real screen). Therefore, we got 2 high tripods, standing a few meters from each other next to the subject, with four tracking plates attached, one at the top and one at the bottom of each tripod.

The question is how to best track the canvas, precision is really important. Using a simple planar tracker doesn't work, because of the moving background between the tripods with a lot of perspective change going on. One idea would be to manually add a rough mask in-between the tripods and feed it into the tracker, to roughly avoid this area. But this doesn't work very well.

My approach would have been to track each of the plates on their own, which works out gorgeously. From there, is there a way to attach a mask with each of its corners positioned relative to a tracker? A mask behaving relative to the four single trackers. Or do you have any other suggestions?

As mentioned, precision is important for this scene.

Kind regards
Simon