Hiding the source in an extreme lighting position to avoid casting shadows can cause distortion in the image and requires correction in the slide to compensate. In this case, the surface should transmit an image with true optical clarity and brightness. A higher intensity source is necessary as the light rays are forced through the surface of the screen to the viewer. By definition the source is masked to the audience, but space must be left backstage between the source and the surface, in order to prevent the actors and crew from casting shadows on , the surface. The darker colors included in the rear projection palette allow the surface to blend inconspicuously into the scenery.
Actors can stand in front of the screen without blocking the image.
Because the image is usually projected on an angle directly perpendicular to the surface, distortion is generally not a problem. If the surface is painted, varied and interesting effects can be achieved by projecting them from behind so that they blend with the painted picture. Day to night effects are a perfect example of this. Rear projection also has its disadvantages. Because of the density of the material required to diffuse the image and prevent hot spotting, the image quality falls off sharply when the viewer is seated outside the 60 to 110 degree viewing cone.