We have come so far these days in VFX. We use computers to do everything, and forget that often the simplest methods are the best. Here is an idea: Put models in front of the camera, and take a picture with real places in the distant background. I think they used that on Aliens and The Abyss, as a matter of fact. (Do not forget the brilliant work in Dune and Conan: the Destroyer.)
For us digital geeks out there, that is a dense point sampled, high dynamic range, global illumination algorithm, with energy preserving reflections — in real time. We call it reality.
Check out the AMAZING work of Michael Paul Smith!
This old Cinemagic can give you aspiring filmmakers some tips on how to do this at home, but substitute digital cameras. It is the work of Mike Minor, and that new up-and-comer Dennis Muren.