Surveillance cameras can track multiple people

The majority of existing pedestrian trackers concentrate on maintaining the identities of targets, however systems for remote biometric analysis or activity recognition in surveillance video often require stable bounding-boxes around pedestrians rather than approximate locations.

Below are two excerpts from Active Vision lab's report, titled Stable multi-target tracking in real-time surveillance video:

"We present a multi-target tracking system that is designed specifically for the provision of stable and accurate head location estimates. By performing data association over a sliding window of frames, we are able to correct many data association errors and fill in gaps where observations are missed."

"The approach is multi-threaded and combines asynchronous HOG detections with simultaneous KLT tracking and Markov-Chain Monte-Carlo Data Association (MCMCDA) to provide guaranteed real-time tracking in high definition video."

Government spying is much, much worse than reported...

3D tracking of multiple objects with identical appearance:
http://www.robots.ox.ac.uk/ActiveVision/Publications/ren_etal_3dv2014/ren_etal_3dv2014.html

Real-time 3D tracking and reconstruction on mobile phones:
http://www.robots.ox.ac.uk/ActiveVision/Publications/prisacariu_etal_tvcg2015/prisacariu_etal_tvcg2015.html