Last Updated 23 hours ago
Filmmaking Dictionary: Letter R / Rear Screen Projection
Definition
Rear screen projection is an in-camera compositing method in which a projector sends a background image through a translucent screen from behind. The filming camera and performers are on the other side. The camera records the foreground action and projected background together.
A familiar application is a vehicle interior filmed in a studio with moving road imagery visible through its windows. The method can also support windows, landscapes and stylised environments.
How the Elements Fit Together
The background plate must suit the foreground camera’s viewpoint, lens impression, horizon and movement. If the plate looks down from a high position while the foreground camera sits low, the combined image may reveal the mismatch even when both elements are sharply photographed.
The projector, screen and camera form an optical system. Screen material and viewing angle affect brightness, contrast and the visibility of a hot spot. Space behind the screen is needed for the projector’s throw or an appropriately designed optical arrangement.
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Lighting and Exposure
Light spilling onto the front of the screen can wash out the projected blacks and reduce contrast. Foreground lighting therefore needs control, while still matching the direction and quality suggested by the background.
Set the balance by testing the recorded picture. The foreground and background should fit the intended scene rather than simply producing matching meter readings. Reflections in glass, glossy surfaces and vehicle interiors can also reveal lights or the studio.
Camera Tests
- Check perspective, horizon height and the direction of background movement.
- Test exposure and contrast with the actual screen and foreground lighting.
- Check projector refresh behaviour against the camera’s frame rate and shutter setting.
- Look for flicker, banding, screen texture, hot spots and visible edges.
- Test actor and camera movement throughout the planned range.
- Confirm that playback can repeat and start at the required cue.
A background that works from one camera position may fail after a move. Rear projection is not automatically a perspective-correct moving environment.
Rear Projection, Front Projection and LED Walls
Rear projection transmits an image through the screen. Front projection reflects projected light from the camera side. An LED wall emits its own image. These arrangements have different space, spill, reflection and viewing requirements.
They can all place a visible background behind a performer, but they are not interchangeable setups. Green-screen photography instead captures material intended for a later key and composite.
See the camera department guide for the crew roles involved in testing and recording the result.
Related Terms
Browse terms beginning with R or return to the filmmaking dictionary.