Camera resolution charts are like eye charts for cameras. They are used to calibrate and focus the instruments. Cameras on airplanes need to be calibrated, too -and the charts for them are there, larger than life, to be used by spy planes and drones, and even by satellites.
The largest concentration of calibration targets in one place is on the grounds of Edwards Air Force Base, in an area referred to as the photo resolution range, where 15 calibration targets run for 20 miles across the southeast side of the base in a line, so multiple targets can be photographed in one pass. There is some variation in the size and shape of the targets at Edwards, suggesting updates and modifications for specific programs. A number of the targets there also have aircraft hulks next to them, added to provide additional, realistic subjects for testing cameras. Some of these planes are themselves unusual and rare military jets, officially in the collection of the base museum, despite being left out on the range.
There are an unknown number of other isolated photo calibration targets across the country, mostly inside restricted groundspace at military areas, such as at Eglin AFB, Florida; the Nevada Test Site; around Walker Field, a Navy drone airport in Maryland; and an especially exotic one at Fort Huachuca, in Arizona. Several others are painted on existing taxiways and runways, such as at Wright Patterson AFB, Ohio; Travis AFB, California; Beaufort Marine Corps Base and Shaw Air Force Base in South Carolina.
Google Earth gives us a view of some of these charts, which you can see at the Center for Land Use Interpretation. They strangely remind one of crop circles, even though they involve neither crops not circles. Link -via PetaPixel