Now, when mass shootings occur, more and more bystanders are starting to record videos on their smartphones, according tomedia. Thanks to a new system, VERA, the videos could quickly find out where the killer was. The system, developed by a team at Carnegie Mellon University, requires three or more smartphones to record video/audio of events at different locations at the same time.
After the 2017 Mandalay Bay Hotel concert shooting in Las Vegas.
First, the system is able to determine the location of each phone in the environment based on recorded images of known buildings and other structures. Next, it “listens” to two sounds in each phone’s audio track. The first sound is the supersonic “crack” that occurs when a flying bullet breaks the sound barrier; the other is the sound of a muzzle explosion, although it actually occurs before the supersonic crack occurs, because it travels only at the speed of sound so it reaches the phone’s microphone instantly.
By analyzing the time between the recorded crack and the explosion, VERA was able to determine how far the phone was from the gun. It can then determine the exact location of the gun by comparing the location of the three phones with the distance between the guns.
The system used smartphone video of the Mandalay Bay hotel incident to pinpoint the gunman’s location based on three shots recorded within a minute of the massacre.