holograph Posted September 20, 2011 Share Posted September 20, 2011 In another thread, there was some discussion about aircraft navigation beacons. Although this is not a beacon, I thought some of you might be interested to see one of the early (1939) aircraft navigational aids. The image below is a "cross-eyed" stereogram of the center of Scranton, Pennsylvania, on June 4, 1939. The images were aerial photos taken for the Agricultural Adjustment Administration and which were digitized and put online at the PennPilot web site. The top of the large tank has been painted with an arrow pointing to the nearest airfield. A pilot, flying visually, would see these signs and be able to find the airfield. I've seen such signs painted on top of barns, too. If you are not familiar with "cross-eyed stereograms", you need to cross your eyes slightly when viewing the image to see the stereo effect. No special glasses required, but it may take a little practice to see it. If you have trouble, try holding a finger near your face, focus on your finger, and move it toward the image until you see the stereo image converge. Quote Link to comment
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