This was the basis for a presentation at the 3D Workshop sponsored by the USDC and Insight Media in South San Francisco, on November 16th, 2006.
Stereoscopic displays have a curious history, because the invention of the fundamental display medium and the discovery of the depth sense of binocular stereopsis occurred simultaneously. Although there were illusions in antiquity that each eye sees different images, there was no clear understanding of what this meant in terms of depth perception until Sir Charles Wheatstone presented On Some Remarkable, and Hitherto Unobserved, Phenomena of Binocular Vision at the Royal Philosophical Society. Wheatstone invented the mirror stereoscope and demonstrated the existence of binocular stereopsis, or “two-eyed solid-seeing,” by presenting drawings that had ambiguous depth cues. My favorite, and possibly the simplest, is a line drawing of a flight of stairs. It’s impossible to tell its volumetric extent from looking at a single view, but there is a visualization revelation when viewed in Wheatstone’s stereoscope. Suddenly you can unambiguously judge depth.