Layering Investagation

Ray Harryhausen, special effects titan of the 20th century.  Among his accomplishments, which are quite numerous, is the method of rear projection.  It was very similar to our current green screens in what its purpose, to fill in backgrounds and add things into the shot that couldn't be in principal photography.  If you've ever seen an older movie with a driving scene in it, you've probably seen rear projection in use.

The process involves taking two pictures on one piece of film to fill in blanks.





 

Ray Harryhausen may not have invented rear projection, but he objectively used it the best and to its fullest potential.  His most famous uses of rear projection are probably Jason and the Argonauts(1963), and Clash of the Titans(1981).


Because of the prevalence and ease of use of modern technology that does its job better than rear projection ever could, it is out of use in most professional and semi-professional films.  Using it with blender would be silly.