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The researchers worked on how to "see" people without using expensive cameras or lidar equipment for years. In 2013, a team of MIT researchers found a way to use mobile phone signals to see across walls. In 2018, another mit team used Wi-Fi to detect people in another room and turn their movements into walking stick figures. Now scientists from Carnegie Mellon University and the University of Waterloo are advancing our ability to see through walls with WiFi.
How you can see through the walls.
Researchers at Carnegie Mellon University have developed a new method to detect 3D shapes and movements of the human body in a room, using only WiFi routers. The team used DensePose, a system for mapping all of the pixels on the surface of a human body in a photo, which was developed by London-based researchers and Facebook’s AI team. This is basically a means of capturing a set of coordinates for each joint as an arm, a head, a torso, etc, that is known to be a key point that can describe the posture of a person. They then created a deep neural network which maps the phase and amplitude of the Wi-Fi signals sent and received by the routers at the coordinates on the human body.
The technology works by sending a low-power Wi-Fi signal through a wall that resonates throughout the room. It detects all objects in the room, cancels static objects, and when the signal bounces, uses the reflection of objects in motion to generate an image similar to a radar. It can operate through standard drywall, wooden fences and even concrete walls, although the scope and precision depend on the type of wall.
Technology and the question of the right to private life.
The Carnegie Mellon researchers believe that WiFi signals “can serve as a ubiquitous substitute” for normal RGB cameras when it comes to “sensing” people in a room. Using the wifi, they wrote, overcomes obstacles such as poor lighting and occlusion as the regular camera objectives face up. They also contend that this technology enhances privacy rights by not relying on cameras and that the required equipment can be purchased at a reasonable cost. Most households in developed countries already have Wi-Fi at home, and this technology can be used to monitor seniors' well-being or identify suspicious behaviours at home.
Researchers at the University of Waterloo have developed a drone-powered device called Wi-Peep that can see through walls using WiFi networks. The device can fly near a building and use the inhabitants' wifi network to identify and localize any Wi-Fi device in the building. Even if a network is password-protected, smart devices will automatically respond to contact attempts on any device in reach. The wi-peep sends multiple messages to an aircraft in flight, then measures the response time on each, allowing it to identify the location of the aircraft within one metre.
What makes Wi-Peep remarkable.
What is particularly interesting about Wi-Peep is its accessibility and ease of transport. The team constructed the aircraft using a store-bought drone and $20 in easy-to-buy equipment. It means that anyone with good expertise could easily create a similar device.
The potential uses of this technology are vast, whether it's an assault on a building by law enforcement, a fire department looking for people in a burning building, or search and rescue. However, privacy impacts are also important, and it is important to consider the potential consequences of using the technology for more sinister purposes.
