Alexander Hellemans of IEEE Spectrum recently reported that a number of drone designers are currently exploring a technique known as optical flow, which is based on the speed of objects passing a subject’s field of vision.
“[We] use optical flow to give us a sense of how fast we’re going when we’re driving,” Hellemans explained. “But unlike humans in cars, drones have a third dimension to worry about. They also have to keep track of their height in order to land successfully.”

