This video has a lot of examples: https://www.youtube.com/watch?v=gUnxzVOs3rk https://www.youtube.com/watch?v=gUnxzVOs3rk Part of the idea is to do as much as

This video has a lot of examples: https://www.youtube.com/watch?v=gUnxzVOs3rk https://www.youtube.com/watch?v=gUnxzVOs3rk Part of the idea is to do as much as possible in-camera, by rendering the virtual surroundings at a high enough quality to directly film them as the actors' backdrop. It's sort of like a wildly more advanced version of using matte painting backdrops. It also seems far better for actor immersion than green screen, as the people on camera get a live wraparound view of the virtual 'set'.