What's the use of giant bar codes all over the United States?

If you fly over some parts of the United States and look down from the air, you can see large-scale "bar codes" everywhere. Their origins can be traced back to the late 1950s. These barcodes are actually calibration points for aerial photography, which were jointly established by the US Air Force and NASA. These patterns are sometimes called 5: 1 triple arrays, which are similar to the magnified resolution patterns in microscopes, telescopes, cameras and scanners.

The fringe in this position is probably the recognition limit of the camera.

Due to the difference of photography technology in the past, it is not as advanced as it is now, and it is still a relatively simple photography method, and aerial photography may not be accurate. Therefore, it is necessary to build these buildings similar to bar codes on the ground for aerial photographers to shoot and calibrate.

Now with the improvement of photography technology, it is no longer used. Although it lost its original function, it can be seen that it was very important at that time.