I had an idea the other day for CGI scenery in a live situation. Imagine a play being adapted for the screen. Something inherently theatrical like Our Town or Mother Courage or a show laden with soliloquies. And one wanted an 'on location' shot to be followed by a monologue/soliloquy in a sterile environment why cut to said scene. What if it's done "in-camera"? The Stage Manager, of Our Town, is interacting with the cast then he addresses the audience the camera moves to reveal that the "location shot" was actually the cyclorama (or a series of flats if one is adapting a show that has some basic scenery). Since most scenery is designed in CAD programs the dimensions should be accurate enough for a CGI team assuming that it's built accurately.

Also why not do said movie/show live. Film it and intersperse these shots into "on location" and sound stage shots. Hell fill the audience with the relatives of the cast members to "remind" the movie audience that it's only a play from time to time. In a shot over the Stage Manager's shoulder revealing the audience, the family members of the more famous members of your cast could be presented.

If the play is episodic in nature, has jumps in time, the jumping out of the movie world to the play world could bring about the use of the old theatrical Unity of Time. The story of Our Town is episodic but the movie of the play would be in 'real time.' A two hour performance of a 30 yr or so story.

Just thinking out loud.