It's a fairly simple process to explain, but it takes a long time and a lot of work to accomplish it. Especially at the level Disney achieved. That end sequence was spectacular.
Do a search here at the COW for "The Kid Stays In the Picture". It was a film that used a lot of pictures that were clearly flat moving in 3d.
It's a similar effect.
You basically freeze your frame, export it to Photoshop, extract the images you want to have separated, then recreate the background behind them so they can move without leaving a hole.
It'd be easiest if after you shot your scene, you removed the actors and shot a blank plate. Then, if you want to have other things move, remove them and shoot another blank plate. That way you have background info you can paste in rather than trying to clone it.
In AE then you just move the different layers in 3d space.
I hope this helps
- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')
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