For all the impressive tasks that drones can do, there is one that remains beyond their power: facial recognition. Drones are generally much farther from their subjects than the kind of cameras, such as CCTVs, that are ordinarily used for biometrics. At these distances a face may consist of only a few dozen pixels. Atmospheric turbulence caused, for example, by rising hot air, can distort features like the distance between one’s eyes. And because they record from the sky, drones’ on-board cameras may capture only a partial view of a face (or, if someone is wearing a wide-brimmed hat, none at all).