Strange designs in China are optometry charts for spy planes

How can you tell if your spy planes and satellites need corrective eye wear? You have them read an optometry chart, of course. The only difference is that instead of reading letters and capital E’s pointed in different directions, they have to discern the patterns scattered around the Gobi Desert and other locations.

The image above found on Google Maps is one of many being discovered by people of the web since they were first spotted in 2011. Here are some of the others that have been located so far.

Like a huge puzzle:

They can be round as well.

… or square.