The expression IMAX descends from the expression "images maximum" and denotes a very large film format. It was developed by a Canadian company for huge screens to make the spectators feel as being part of the scenery. Different from the "usual" cinematic movies, this technique uses very much larger picture formats, high-powered projectors with Xenon-bulbs, and horizontal transportation of the film reel. Several other mechanisms care for a brilliant, sharp and flickerless image. Due to technical and economical constraints, most of the produced movies have a scientific content. Several variants of IMAX theaters have been developed to bring the adventure closer to the visitors. In particular, planetaria use the system "IMAX Dome" (formerly called "Omimax"). Here, the projector is located close to the geometrical centre of the building instead of the rear projection. Since the screen is curved, a lot of special features about the camera, the lenses as well as the projecting devices have to be considered. Most of all: Distortions to the edge must be corrected. The seats in the IMAX Domes are unidirectional and tilted (most often: 20°). As such, only one half of the hemispheric dome is deployed, but not the full hemisphere as a planetarium with concentric seats would do.