Matte painting creates large, realistic landscapes without the expense of location shooting or building elaborate sets. A large sheet of glass is painted with a background, such as a mountain range. A section of the glass is left unpainted and a set is built to match the areas of the scenery that would have filled that portion of the painting. The cinematographer then hangs the glass in front of the camera, positioning it so that the unpainted sections of the glass allow the camera to record the set behind them. Only the parts of the set that will be used by the actors need to be built when using this method. This technique persisted for decades until the advent of CGI, or computer-generated imagery. Look to the "Star Wars" movie franchise for modern examples of matte painting, such as the establishing shot of Cloud City in "The Empire Strikes Back" (1980). Matte paintings were used in nearly every landscape shot because the "Star Wars" settings required entire alien worlds and massive star ships.
Rear projection, like matte painting, adds large, realistic backdrops to a scene. Because the background is a projection of another film, pre-recorded stock footage, such as scenes from a busy town square, can be used to create movement and a more realistic backdrop for the scene. Alfred Hitchcock was particularly fond of this technique. His 1946 film "Notorious" was shot almost entirely indoors, with outdoor scenes done with rear projection backdrops. A modern equivalent of this is the well-known green screen, in which a blank green screen is shot as the background. The color green can be removed later by computers and replaced with other footage.
Stop motion animation is a technique where a small model is created, filmed, adjusted, and then filmed again. This technique laboriously creates a film one frame at a time, but allows the filmmaker to create a scene featuring realistic creatures that otherwise would require expensive animatronics. Famous examples of stop motion animations include "King Kong" (1933) and "The Lost World" (1925), both animated by Willis O'Brien.
Ray Harryhausen, a student of "King Kong" animator Willis O'Brien, refined stop motion animation by combining it with rear projection and matte painting. His technique, called Dynamation, worked by projecting an image onto a screen sitting behind a clay model. The model and background projection were then shot through a matte painting that made up the foreground. The combination of all three techniques could create complicated, multi-layered scenes that none of the techniques could reproduce separately. For example, a filmmaker using this technique could paint a ravine setting for two dinosaurs to do battle, while a landslide is rear projected behind the scene to give movement to the backdrop.