The two 16-mm films ROTATIONS and PROJECTIONS (originally ROTATIONEN and PROJEKTIONEN) used one of the earliest three-dimensional programs for the graphic real-time output as a projection on a two dimensional screen. They were calculated and displayed with an interactive graphic screen of the Siemens Research Laboratory, Munich, in connection with a digital data processing unit. The unit allowed interactive operation – work under interactive visual control; a keyboard was used to change the elements interactively – for example, by specifying the number of picture elements, the angle of intersection, the speed of the sequence, and so on. The movement could be stopped for a static image at any time.
