Eye Tests for Drones

By Norman Chan

Explaining these strange optical landmarks in the middle of America.

The Center for Land Use Interpretation explains how, across the United States, there are dozens of photo calibration charts painted on concrete or asphalt pads in the middle of deserts and fields for camera testing. These are line bar tests similar to what photography reviewers use to assess the accuracy of film cameras, but made for aerial cameras mounted on spy planes and drones. The charts are outdated now, given how digital sensors work at high speed. (h/t kottke)