The rotoscope has also been used as a tool for special effects in live-action movies. By tracing an object, a silhouette (called a matte) can be created that can be used to create an empty space in a background scene. This allows the object to be placed in the scene. Such a technique, of creating mattes by hand, was used in the movie 2001: A Space Oddyssey. Because of this special-effects usage, in computer graphics, to rotoscope is to create an animated matte indicating the shape of an object or actor at each frame of a sequence, as would be used to composite a CGI element into the background of a live-action shot.