Although Avatar heralded a new, oft-debated era of 3-D movies in late 2009, James Cameron's technology was actually predicated by that of DW Griffith, who previously created The Birth of a Nation, America's first blockbuster. In 1923, movies still lacked color and sound, but Griffith claimed to have developed stereoscopic movies that "would drive startled spectators from their seats." Here's how it'd work: a stereoscoping movie camera would exposes red and green, left and right films simultaneously while filming. Audiences would watch movies using an alternating shutter device, which would filter double-image pictures so that the viewer sees the "right" picture with his right eye, and then the reverse an instant later. How's that for a predecessor to 3-D glasses?
Read the full story in "Thrills 'Leap from Screen' in Stereoscoping Movies"