From Brian Horton, West Launceston, Tasmania, Australia
The US military is developing a face-recognition device that could be accurate from a kilometre away (22 February, p 13). The idea seems to be to use this on drones, which will presumably act when detecting a person of interest.
A separate prize challenge for such a system, from the US National Institute of Standards and Technology, allowed a false match rate of one in 1000 people. This may sound impressive, but if a drone with this technology is flying past a village of 1000 or so people, it will almost certainly pick one of them in error as a target.
