In August 2016, Bloomberg Businessweek revealed the existence of a pilot program being operated by the Baltimore Police Department in which small manned aircraft circled over the city all day, using cameras to continuously photograph a 32-square-mile area and giving police the ability to retroactively track any vehicle or pedestrian within that area. It was the ultimate Big Brother “eye in the sky”—and yet the Baltimore police had not notified the public or even the mayor or city council about the program. Revelation of the secret program generated a storm of controversy, and eventually it was put on hold—though in December 2019, the city’s police commissioner announced that the program would be revived.
The technology behind the Baltimore program involves pointing multiple cameras toward the ground and stitching those images together into a single, larger photograph. It also uses computers to automatically correct for the changing camera angles of the circling planes as well as factors such as topographic variances and lens distortion.
The result is a surveillance system of enormous power, able to reconstruct the movements of all visible vehicles and pedestrians across a city—where they start and finish each journey and the paths they take in between. It can allow tracking of a great proportion of people’s movements throughout a city.