A front projection effect is an in-camera visual effects process in film production for combining foreground performance with pre-filmed background footage. Working
In contrast to rear projection, in front projection the background image is projected on to both the performer and the background screen. This is achieved by having a screen made of Scotchlite, a product of the 3M company that is also used to make screens for movie theatres. Scotchlite is made from millions of glass beads cut in half and affixed to the surface of the cloth. These glass beads reflect light back only in the direction in which it came, far more efficiently than any common surface. In fact, Scotchlite is 1000 times more reflective than the human body.
The actor (or horse or spaceship, etc.) performs in front of the Scotchlite with a movie camera pointing straight at him. In front of the movie camera is a one-way mirror angled at 45 degrees. At 90 degrees to the camera is a projector which casts a faint image of the background on to the one-way mirror which then reflects the image back at the performer and the Scotchlite; the image is too faint to appear on the actor but will show up clearly on the Scotchlite. In this way, the actor becomes his own matte. The combined image is then reflected back through the one-way mirror and is recorded by the camera.
2001: A Space Odyssey is commonly believed to be the first movie to make use of front projection for the "Dawn of Man" sequence. The 1967 monster film Equinox made use of it first. The actors in ape suits were filmed on a stage at Elstree and combined with footage of Africa. (The effect is almost flawless except for the glowing cheetah's eyes reflecting back the light.) Zoptics
Front projection was chosen as the main method for shooting Christopher Reeve's flying scenes in Superman: The Movie. However, they still faced the problem of having Reeve actually fly in front of the camera. Yugoslav effects wizard...