Is the Person in Video Behind This Wall?

This post is also available in: עברית (Hebrew)

Identifying a person through walls from video footage is a considerably challenging problem. A new technique can determine if the person behind the wall is the same as the one in a video footage, by using only a pair of off-the-shelf WiFi transceivers outside.

The technique is referred to as Cross Modal Identification, and it has a lot of potential uses particularly in the field of law enforcement.

Researchers from the Santa Barbara campus of the University of California discovered that WiFi signals could be used to locate people through hard walls. Basically the WiFi signals will be used to analyze someone’s walking gait, and if the gait matches what is on record then this would be a successful identification which would make it possible to locate that person time and time again.

WiFi signals have been used previously to 3D map a room through a hard wall, though this is the first time that people have been successfully identified using nothing but the WiFi signals that are in their rooms, according to digitalinformationworld.com. 

The major applications could be:

In the sphere of security and surveillance – consider the scenario where the video footage of a crime scene is available and the police is searching for the suspect. A pair of WiFi transceivers outside a suspected hide-out building can use the technology to determine, from outside, if the person in the crime video is hiding inside. Moreover, the existing WiFi infrastructure of public places can further be used to to detect the presence of the suspect, by referencing the crime-scene video footage, according to ece.ucsb.edu.

In the home security field – consider a smart home, where each resident has personal preferences (e.g., lighting, music, and temperature). The home WiFi network can use XModal-ID and one-time video samples of the residents to identify a person walking in an area of the house and activate his/her preferences, without the need to collect wireless/video data of each resident for training purposes. New residents can also be easily identified without a need for retraining.

However, If the technology ends up in the wrong hands it could be disastrous to privacy because of the fact that pretty much everyone uses WiFi in order to access the internet.