It is now possible to take 3D pictures of the inside of a room or building — from the outside — with Wi-Fi.
The technology, described in the journal Physical Review Letters, is still in the development stage, although its impact on privacy is frightening.
“You could probably use a drone to map out the inside of an entire building in 20 to 30 seconds,” Philipp Holl, an undergraduate at the Technical University of Munich, told Business Insider.
Holl is one of the inventors of the new kind of holography that can turn Wi-Fi  into a surveillance tool.
“It can basically scan a room with someone’s Wi-Fi transmission,” Holl said.
How it Works
Wi-Fi devices that can take pictures through walls have been around for years but the image quality was terrible, Business Insider noted. Holl and his academic supervisor, Friedemann Reinhard, discovered how to take higher-resolution pictures through walls using Wi-Fi.
“Our method gives you much better images, since we record much more signal,” Holl said. “We scan the whole plane of a room.”
They use two antennas. One antenna stays in a fixed position to capture the background while the other is moved to get a complete picture.
The data captured is simultaneously fed into a computer, where software sorts out the differences and creates a real-time picture. The software can create many two-dimensional (2D) images that are combined to create a three-dimensional (3D) picture or hologram.
“These antennas don’t need to be big,” Holl said. “They can be very small, like the ones in a smartphone.”
Some uses of the technology could be beneficial, such as finding people in an earthquake rubble. But other uses – such as by spy agencies or police – will be more controversial.
It looks as if those of us who want privacy had better go back to connecting to our devices the old-fashioned way — with cables.
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