The new ubiquitous use of green screen.
Use of the green screen, or chroma key, is not a new technique. In fact variations of this very useful tool have been around since the 1950’s. As computing power continues on its exponential rate of growth, so too does the usefulness of this incredible tool.
The basic function comes from the delineation of a matte, or outline, of a subject that is to be placed in some other setting or engaging with things not in the location. This matting process is created by using a clean, evenly and well lit green (or other colored) screen behind the subject. In the edit process the green screen is then separated and the outline matte that travels with the motion of the subject is created.
The digital tools for doing this are called Chroma keyers and are now integrated into most professional edit programs such as Final Cut or Premiere. This allows for very creative placement of the subject into a near limitless potential of locations.