I'm trying to figure out how to do something- we're going to build a set on a stage and cover the floor in sand, and throw up a green screen wall around the edges of the set with tracking markers. We're going to digitally extend the set by continuing the sand far off into the distance and matte painting the background. (This has to be filmed inside for reasons I wont go into).
I know how to do this in 2d with a locked camera, but really I want to be able to move the camera around freely with perspective changes and maybe even large pans. Could anyone tell me the official way to extend the floor?
I've tried turning the matte painting into a 3d projection mapping so that the extended sand moves in perspective but if the camera moves too much the illusion starts to break and get distorted.
Are there any good tutorials out there on 3d tracking a green screen and extending the set digitally? I'd prefer to keep it in After Effects but if it has to be done in a 3D programme I'll learn it if someone can point me in the right direction.