Event Reconstruction System Uses Smartphone Video to Locate Shooters

A system that can accurately locate a shooter based on video recordings from as few as three smartphones has been developed by researchers at Carnegie Mellon University. The system, called Video Event Reconstruction and Analysis (VERA), uses machine learning techniques to synchronize the video feeds and calculate the position of each camera based on what that camera is seeing.

VERA looks at the time delay between the crack caused by a supersonic bullet’s shock wave and the muzzle blast, which travels at the speed of sound. It also uses audio to identify the type of gun used, which determines bullet speed. VERA can then calculate the shooter’s distance from the smartphone. By using video from three or more smartphones, the direction from which the shots were fired and the shooter’s location can be calculated based on the differences in how long it takes the muzzle blast to reach each camera.

When demonstrated using three video recordings from the 2017 mass shooting in Las Vegas, the system correctly estimated the shooter’s actual location — the north wing of the Mandalay Bay hotel — based on three gunshots fired within the first minute of what would be a prolonged event.

A system developed by Carnegie Mellon University uses video from smartphones to help pinpoint the location of shooters. Here, analysis of video from two smartphones during the 2017 mass shooting in Las Vegas indicates the shooter was in the north wing of the Mandalay Bay hotel. Courtesy of Carnegie Mellon University.

VERA won’t replace the commercial microphone arrays for locating shooters that public safety officials already use, but could be a useful supplement for public safety when commercial arrays aren’t available. It is an event analysis system that could be used to locate a variety of other sounds, besides detecting gunshots, the researchers said.

The research team presented VERA and released it as open-source code at the Association for Computing Machinery’s International Conference on Multimedia held Oct. 21-25, 2019, in Nice, France.

Researchers at Carnegie Mellon University have developed a system that can accurately locate a shooter based on video recordings from as few as three smartphones. Courtesy of Carnegie Mellon University.