HISTORY OF STEREOSCOPIC IMAGING
Charles Wheatstone discovered the principle of stereo 3D in 1832, before photography. He experimented with simple drawings and a mirror stereoscope he designed. Soon stereo was being applied to photographs, both by dual lensed cameras as well as be shifting the camera for left and right views (for subjects that are not moving). At the turn of the century, "stereopticon" type stereoscopes were very popular and several companies produced anatomical studies in 3D.