Scientists can take 3D hologram pics through walls using Wi-Fi

Wi-Fi is everywhere - and as the electromagnetic waves are beamed out from routers to connect our devices to the internet, they also travel through empty space, around corners, and even through walls.

A pair of German researchers have developed a method to harness Wi-Fi signals to capture 3D hologram images of objects around a network, even through solid barriers like doors and walls.

The key is recording the shapes made by stray radiation, the electromagnetic waves that bounce off objects as they travel through the air.

The research behind the 3D-imaging method, which started as an undergraduate thesis project before being fleshed out into a larger study, was originally published in the Physical Review of Letters earlier this month.

The technique described in the study was able to provide images as often as 10 times a second and recreate the contents of an entire building in a large-scale simulation.

Using Wi-Fi for imaging isn't a new concept - but the authors of the paper behind this new breakthrough claim it's the first time the signals have been used to produce 3D hologram recreations of large spaces.

The system isn't accurate enough to distinguish many details for now - but if you're only looking to identify individual shapes or figures within the space, it works.

"If there's a cup of coffee on a table, you may see something is there, but you couldn't see the shape," Philipp Holl, a Technical University of Munich physics student who coauthored the study, told Business Insider.

"But you could make out the shape of a person, or a dog on a couch. Really any object that's more than four centimeters in size."

The method uses Wi-Fi signals to essentially scan a room, acting as a low-powered radar rig.

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