How complete is the technological surveillance net? Even in the United Kingdom, which may have the world’s highest density of security cameras, there are plenty of gaps. But those may be closing. University of London researchers report they may have solved the tricky problem of how to track suspects when there are blind spots between one security camera and the next—what is known in the industry as “nonoverlapping” camera networks.

Most solutions rely at least partially on appearance matching, using distinguishing visual features to track a suspect as he or she moves between security cameras. But this approach doesn’t work in instances where the quality of a feed isn’t good enough to pick up details.