a specialized, big-screen film format about ten times larger than the traditional cinema format (35mm) and three times larger than the standard 70 mm widescreen format; debuted in Osaka Japan at the 1970 Exposition; IMAX films, often short documentaries, 'educational,' travelogue or nature films, are shot and projected on 15 perforation/70mm gauge film - "15/70", the largest film format in existence, which produces incredible high-definition sharpness in films projected on up to eight-story high screens in theatres equipped with advanced digital surround-sound systems; IMAX projection onto a domed screen is called Omnimax