Abstract: For a field to be surveyed, generating at least first and second flight plans, the first flight plan including a plurality of first way points, the second flight plan including a plurality of second way points, each of the second way points corresponding to one of the plurality of first way points, each of the first and second plurality of way points being together suitable for photographing an entirety of the field to be surveyed; and executing, in parallel, the first and second flight plans by corresponding first and second drones, the executing including, at each of the corresponding ones of the first way points and the second way points, simultaneously photographing first and second at least partially overlapping sections of the field by corresponding first and second drones, obtaining an absolute position of each of the first and second drones, and measuring a distance between the first and second drones.