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Wireless vision able to capture images behind walls

Posted: 02 Nov 2015 ?? ?Print Version ?Bookmark and Share

Keywords:MIT? WiFi? wireless? RF? camera?

Researchers at MIT's Computer Science and Artificial Intelligence Lab (CSAIL) have always considered the possibility that wireless signals such as WiFi have the capability to see things that are invisible to the naked eye.

Since 2013, a CSAIL team has been developing technologies that use wireless signals to track human motion. The team has revealed that it can detect gestures and body movements as subtle as the rise and fall of a person's chest from the other side of a house, allowing a mother to monitor a baby's breathing or a firefighter to determine if there are survivors inside a burning building.

Next up? Seeing a person's silhouette and even distinguishing between individuals.

In a paper accepted to the SIGGRAPH Asia conference taking place next month, the team showcased a technology called RF Capture that picks up wireless reflections off the human body to see the silhouette of a human standing behind a wall.

RF Capture

By seeing silhouettes through a wall, CSAIL device could help with motion capture, fall prevention and even your heating bill.

By tracking the silhouette, the device can trace a person's hand as he writes in the air and even distinguish between 15 different people through a wall with nearly 90 per cent accuracy.

In other words, from the opposite side of a building, RF Capture can determine where you are, who you are, and even which hand you are moving.

From heating bills to Hollywood

Researchers said the technology could have major implications for everything from gaming and filmmaking to emergency response and eldercare.

Take, for example, motion capture in movie production: "Today actors have to wear markers on their bodies and move in a specific room full of cameras," said PhD student Fadel Adib, who is lead author on the paper. "RF Capture would enable motion capture without body sensors and could track actors' movements even if they are behind furniture or walls."

The device's motion-capturing technology makes it equally valuable for smart homes, according to MIT professor and paper co-author Dina Katabi.

"We're working to turn this technology into an in-home device that can call 911 if it detects that a family member has fallen unconscious," noted Katabi, director of the Wireless@MIT centre. "You could also imagine it being used to operate your lights and TVs, or to adjust your heating by monitoring where you are in the house."

Future versions could be integrated into gaming interfaces, allowing you to interact with a game from different rooms or even trigger distinct actions based on which hand you move.

"The possibilities are vast," stated Adib, whose other co-authors include MIT professor Fredo Durand, PhD student Chen-Yu Hsu, and undergraduate intern Hongzi Mao. "We're just at the beginning of thinking about the different ways to use these technologies."

How it works

The device works by transmitting wireless signals that traverse the wall and reflect off a person's body back to the device. (The emitted radiation is about 1/10,000 the amount given off by a standard cellphone.) The device captures these reflections and analyses them in order to see the person's silhouette.

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