- “Three Tri-bar targets remaining at Cuddeback Lake are visual analog relics of the aerial viewing revolution, and they may be the only ones on public land.”
“THERE ARE DOZENS of aerial photo calibration targets across the USA, curious land-based two-dimensional optical artifacts used for the development of aerial photography and aircraft. They were made mostly in the 1950s and 1960s, though some apparently later than that, and many are still in use, though their history is obscure.”
In Nederland zijn het ronde stippen, Jeroen Jongeleen deed er ooit een project mee in de buurt van Hoek van Holland(?).