Front projection effect

A front projection effect is an in-camera visual effects process in film production for combining foreground performance with pre-filmed background footage.

Description

In contrast to rear projection, in front projection the background image is projected onto both the performer and a highly reflective background screen, with the result that projected image is bounced off the screen and into the lens of a camera. This is achieved by having a screen made of a retroreflective material such as Scotchlite, a product of the 3M company that is also used to make screens for movie theaters. Such material is made from millions of glass beads 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.

The actor (or subject) performs in front of the reflective screen with a movie camera pointing straight at him. Just in front of the camera is a two-way mirror angled at 45 degrees. At 90 degrees to the camera is a which projects an image of the background onto the mirror which reflects the image onto the performer and the highly reflective screen; the image is too faint to appear on the actor but shows up clearly on the screen. In this way, the actor becomes his own matte. The combined image is transmitted through the mirror and recorded by the camera.

The technology needed for front projection was available since the invention of Scotchlite in the 1940s, but apart from some minor technical experiments in 1949, the process was not used for feature films until 1966, during the filming of . The actors in ape suits were filmed on a stage at Elstree Studios and combined with footage of Africa (the effect is revealed in the glowing cheetah's eyes reflecting back the light). Dennis Muren used a very similar solution for his 1967 debut film Equinox, although Muren's technique didn't employ Scotchlite. Two British films released in 1969, On Her Majesty's Secret Service and The Assassination Bureau, used the technique.

Front projection was invented by William F. Jenkins, better known to readers of science fiction by his pen name as Murray Leinster. Jenkins gives an account of the genesis and development of his invention in the November 1967 issue of Analog Science Fact & Fiction magazine.

Zoptic

Front projection was chosen as the main method for shooting Christopher Reeve's flying scenes in Superman. However, they still faced the problem of having Reeve actually fly in front of the camera. Effects wizard Zoran Perisic patented a new refinement to front projection that involved placing a zoom lens on both the movie camera and the . These zoom lenses are synchronized to zoom in and out simultaneously in the same direction. As the projection lens zooms in, it projects a smaller image on the screen; the camera lens zooms in at the same time, and to the same degree, so that the projected image (the background plate) appears unchanged, as seen through the camera. However the subject placed in front of the front projection screen appears to have moved closer to the camera; thus Superman flies towards the camera. Perisic called this technique "Zoptic". The process was also used in two of the Superman sequels (but not used in the fourth movie due to budget constraints), Return to Oz, Radio Flyer, High Road to China, Deal of the Century, Megaforce, Thief of Baghdad, Greatest American Hero (TV), as well as Perisic's films as director, Sky Bandits (also known as Gunbus) and The Phoenix and the Magic Carpet.

IntroVision

IntroVision is a front projection composite photography system using a pair of perpendicular reflex screens to combine two projected scenes with a scene staged live before the camera in a single shot. It utilizes a camera, two projectors, and respective associated three half-silver mirrors/beam-splitters. It allows foreground, midground and background elements to be combined in-camera: such as sandwiching stage action (such as actors) between two projected elements, foreground and background.

IntroVision was first used in 1980-81 during the filming of the science-fiction movie Outland to combine star Sean Connery and other performers with models of the Io mining colony. It was also used in the telefilm Inside the Third Reich to place actors portraying Adolf Hitler and Albert Speer in the long-destroyed Reichstag, as well as Under Siege, Army of Darkness and The Fugitive, where it seemed to place Harrison Ford on top of a bus that was then rammed by a train. Adventures in Babysitting employed IntroVision to place children in multiple situations of peril such as hanging from the rafters and scaling the "Smurfit-Stone Building" in Chicago, and Stand By Me used IntroVision during the train sequence. Most movie companies brought small units to the IntroVision sound stages near Poinsettia and Santa Monica Boulevard in Hollywood, California. Scenes were often shot near the end of the production schedule to allow for the shooting of "live" plates to have been done while on location.

Front projection versus other techniques

Front projection had several advantages over its main rival, bluescreen matte photography: including clipping, mistached mattes (out of sequence), film shrinkage, black or blue haloing, garbage matte artifacts, and image degradation/excessive grain. It could be less time consuming — and therefore less expensive — than the process of optically separating and combining the background and foreground images using an optical printer. It allowed the director and/or director of photography to view the combined sequence all at once, allowing for such effects to be filmed more like a regular sequence, and the performers could be specifically directed to time their actions to action or movement on the projected images. However, advancements in digital compositing and the increasing use of digital cameras have made digital the most common method of choice. The last major blockbuster to extensively use front projection was the Sylvester Stallone action thriller Cliffhanger from 1993. Stanley Kubrick, a long time advocate of the process, also used front projection in his last film Eyes Wide Shut (1999) for some of the scenes requiring the actors to walk down streets.

See also

Film production

References

External links

Article with detailed method

Category:Film production Category:In-camera visual effects