David Marr pioneered the mathematical analysis of vision. In his research, he studied such questions as how depth is perceived, how motion is perceived, and what defines boundaries in the visual field. He claimed that to process nearly infinite combinations, the brain must operate on visual information in certain mathematical ways and have the ability to be finely tuned on many different scales. He intensively studied the fly visual system, working out many of its details. His work has been incredibly important, not only in the understanding of human vision, but in creating the possibility of machine vision.