The human brain is an interesting and curious device. It takes in millions of inputs a second using our five senses and creates an experience of the world around us. This umwelt defines how we interact with the world. It can also be tricked.
In 1838, Sir Charles Wheatstone invented a method of viewing photos that would trick the brain into thinking it was looking at a 3D image. While it spent most of its early life as a novelty item, stereoscopy played a huge role in the Allies photo reconnaissance program.
A photo reconnaissance plane, usually a Spitfire, would fly over Germany or Reich-held territories. They would find the site they were supposed to photograph, then fly straight and level over it with the cameras rolling. The cameras would record images that could be studied in a conventional manner, or two photos could be put side-by-side and viewed through a stereoscope like the lead photo. The stereoscope would help each eye focus on the image in front of it. Since each image was offset by the same proportion as the offset in our eyes, the brain would think it was seeing the same image. The slight offset would trick the brain into seeing it in 3D by letting the brain see occlusions, linear perspective, and even a sense of depth.
This became critical as Allied photo interpreters. It was through stereoscopic photographs of Peenemünde that the V-2 rocket was discovered. It was through stereoscopic photographs of the French coast that the launch ramps for the V-1 were discovered. No fancy computers. Just a special pair of glasses and a human playing tricks on his or her brain.
So, when you put on the goofy glasses to watch your fancy 3D TV, just think about the pilots and photo interpreters who helped the good guys win the last world war.
[Image Credit: Public Domain]
This method is or maybe was used to compile inventory data for Provincial forestry databases.
Didn't they continue to use this method up through the '60s and '70s, with the OXCART and SR-71 cameras? I seem to remember seeing something about it, but I'll be damned if I can remember where. Stupid brains, easy to fool and full of holes.
I believe so. My Father was a cartographer and I remember him using the glasses for certain mapping procedures in the early '70's.
You can also view stereograms without a stereoscope by crossing your eyes though I don't recommend it for any real length of time. I've viewed a fair number of aerial photos with this trick.
You know, I've tried that trick and I've never gotten it to work. I could never see those odd pictures from a few years back that didn't look like anything until you held it at the right distance and crossed your eyes, either. Just not wired right, I guess.