garymortimer writes: "This technology, developed in the Autonomous Systems Laboratory at ETH Zurich, has two weighty advantages compared with GPS-based flying robots. First, it works both in the open air and in enclosed spaces. The second is that the flying robots can navigate where GPS fails; for example, due to the density of buildings. The camera-based technology allows for a more accurate positioning of the aircraft than is possible with GPS, explains the project coordinator, Davide Scaramuzza. Depending on the environment, GPS errors can be as great as 70 metres — much too imprecise when several flying robots are in close proximity to each other in the air."