US Patent 10029790 Device that controls flight altitude of unmanned aerial vehicle

A device that controls the flight altitude of an unmanned aerial vehicle having mounted thereon an imaging device that captures an image of the ground, the device being provided with: one or more memories; and circuitry which, in operation, recognizes, as a plurality of markers, a plurality of objects located on the ground from the image captured by the imaging device, calculates the area of a polygon formed by the plurality of markers, and controls the flight altitude of the unmanned aerial vehicle in such a way that the area of the polygon is maximized.