Rear View Projection.
Rear projection is a special effect technique that is used in film productions. It is the effect of combining the foreground with an existing background that could be filmed beforehand or painted or computer generated images (CGI). It is commonly used in the film industry, mainly in driving scenes or to show some form of background motions. This effect is to create an illusion that the characters are in a place they are not in, very similar to a blue/green screen effect.
The actors would have to stand in front of a giant screen while a projector is positioned behind it to show an image for the necessary background. The background usually would appear much fainter than the foreground, and it could be a still image or a moving image, but they are both called the “plate” and one might also hear “Roll plate” in a film set where rear projection is used to instruct the crew to begin the projection.
In order for rear projection to work and not showing any faults in the plate, the sound stage camera has to be in perfect synchronization with the projector. Both the camera and the projector have to be operating at 24fps, so that there will be no fringes or any halos appearing in the screen.
The rear projection was mainly used to film actors in driving or any moving vehicle scenes, which is in fact a vehicle prop that is set up in front of the plate. In such cases, the actor would seem very odd compared to the projected background, because the projected background was not shot steadily and the bumping movement of the background was not recreated by the actors.
The more you know!