An expanded tri-bar array at Fort Huachuca, Arizona: The targets function like an optician's eye chart,
with the smallest group of bars discernable marking the limit of the resolution for the camera being tested
Is someone scanning the Earth? The mystery of the barcodes painted on the ground across the world
A standard tri-bar test pattern off the runway at Walker Field, Maryland: These mysterious QR code-like patterns
painted across dozens of locations in the U.S. are used to calibrate airborne and satellite cameras
* Car park-sized patterns used to calibrate lenses on planes and satellites
* Most built in the Fifties and Sixties at an unknown number of U.S. locations
* They have become obsolete thanks to new digital imaging systems
This pattern, sometimes referred to as a 5:1 aspect Tri-bar Array, is similar to those used to determine the zoom resolution of microscopes, telescopes, cameras, and scanners.
The targets function like an optician's eye chart, with the smallest group of bars discernable marking the limit of the resolution for the camera being tested, according to the CLUI.
'For aerial photography, it provides a platform to test, calibrate, and focus aerial cameras traveling at different speeds and altitudes,' the CLUI adds.
'The targets can also be used in the same way by satellites.'
Read more: http://www.dailymail.co.uk/sciencetech/article-2280445/The-mysterious-barcodes-painted-ground-world-actually-used-calibrate-airborne-cameras.html#ixzz2NT17KTYr
THE CENTER FOR LAND USE INTERPRETATION: http://www.clui.org/newsletter/winter-2013/photo-calibration-targets