The first segment, which shows the exterior of the Death Star, is based entirely on the VG3D's internal display capabilities. The model consisted of a simple series of 3D points representing the outline of the station held in the PDP-11's memory, constructed algorithmically using the associated GRASS programming language's curve generation code. To move and rotate the image as seen in the film, the associated GRASS program would load new rotation and zoom figures into the terminal's registers and then trigger the camera.
