The need to visualise and display images led to the invention in the 1880s of the epidiascope, the forerunner of today's overhead projector. The introduction of motion picture film in 1929 gave rise to the very popular 35m slide and 16mm motion film projectors. In the 1980s, multimedia and multi-projector presentations became the choice with the advent of computer-aided audio-visual productions and control. The rapid development of the PC and LCD have resulted in today's era of digital presentation systems.