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Science Technology

Scientists Are Getting Eerily Good at Using WiFi to 'See' People Through Walls in Detail (vice.com) 41

Posted by msmash from the how-about-that dept.
Researchers at Carnegie Mellon University developed a method for detecting the three dimensional shape and movements of human bodies in a room, using only WiFi routers. From a report: To do this, they used DensePose, a system for mapping all of the pixels on the surface of a human body in a photo. DensePose was developed by London-based researchers and Facebook's AI researchers. From there, according to their recently-uploaded preprint paper published on arXiv, they developed a deep neural network that maps WiFi signals' phase and amplitude sent and received by routers to coordinates on human bodies. Researchers have been working on "seeing" people without using cameras or expensive LiDAR hardware for years. In 2013, a team of researchers at MIT found a way to use cell phone signals to see through walls; in 2018, another MIT team used WiFi to detect people in another room and translate their movements to walking stick-figures.
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Scientists Are Getting Eerily Good at Using WiFi to 'See' People Through Walls in Detail More

Scientists Are Getting Eerily Good at Using WiFi to 'See' People Through Walls in Detail

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  • At 1000 Ghz (Score:3)

    by Marxist Hacker 42 ( 638312 ) * <seebert42@gmail.com> on Wednesday January 18, 2023 @03:26PM (#63220500) Homepage Journal

    This will begin to be used for porn.

    Current Wifi could, at best, resolve maybe 5cm "pixels" in 3 dimensions. It's going to be a long time before we get this down to the submilimeter zone you'd need for porn or health screenings.

    • It's still plenty enough resolution to create a security risk.

    • Current Wifi could, at best, resolve maybe 5cm "pixels" in 3 dimensions.

      What? Are you're going to sit there and tell me that someone with a sub 7 figure UID hasn't fapped to pixel art before?

  • They invented radar.

    • Passive radar pose estimation based on the amplitude and phase modulation of 3x3 MIMO wifi carriers for 5 samples during 50 milliseconds specifically.

      Not really what I imagine when I just hear radar.

    • Not really. It's actually both obvious in hindsight (there's a reason why microwaves run at 2.4GHz, and human bodies are mostly water) and very clever.

      From a scan of the paper it looks like it won't work with 5Ghz WiFi, so that's one defence.

  • Law enforcement? (Score:5, Interesting)

    by bunyip ( 17018 ) on Wednesday January 18, 2023 @03:34PM (#63220526)

    This will get really interesting for law enforcement, especially in the US. The 4th amendment protects against a lot of unreasonable searches, but could the police argue that you're broadcasting your position through the walls and they are allowed to capture that information from a public place (i.e. the middle of the street)? This is going to get interesting...

    • Re:Law enforcement? (Score:5, Informative)

      by dasunt ( 249686 ) on Wednesday January 18, 2023 @03:46PM (#63220548)

      This will get really interesting for law enforcement, especially in the US. The 4th amendment protects against a lot of unreasonable searches, but could the police argue that you're broadcasting your position through the walls and they are allowed to capture that information from a public place (i.e. the middle of the street)? This is going to get interesting...

      There's been a similar case - Kyllo v. United States [wikipedia.org], where SCOTUS determined that using thermal cameras to observe heat radiation from a home was a violation of the fourth amendment.

      That was over 20 years ago, and the court is very different today.

      • First, did no one else think Batman (The Dark Knight) ? :) Second, I agree, this will be legal, unless it's used on the Justices themselves.

      • Re: (Score:3)

        by tlhIngan ( 30335 )

        There's been a similar case - Kyllo v. United States, where SCOTUS determined that using thermal cameras to observe heat radiation from a home was a violation of the fourth amendment.

        That was because thermal cameras were relatively rare 20 years ago and generally only owned by law enforcement (and businesses) because of their relatively high cost. Thus using equipment not in common availability was considered a violation.

        Things are different today because you can get cheap thermal imagers for your phone fo

    • To make home invasions great again and all that. Case out when and where you sleep, break in when you're not around.
      Or when you are, if they're into that sort of thing.

      Fortunately, we already have everything we need for hunter-seeker drones armed with flechette rounds.

      • Somehow, I doubt small scale criminal use is around the corner. I don't think most people breaking into homes have many resources (and I suspect, that many of those, are addicts).

        • They're already using stingray-like devices coupled with malware to track people via their phones. They don't need exotic new tech.

      • If you gave this hardware to a person desperate enough to break into people's homes for drug money, they would just sell it for drug money.

    • They're not allowed to hack your router to install the custom firmware.

      But the spooks do it anyway which sparked a Third Amendment case a few years back.

      The new "Church" Committee should look into it.

      • But the spooks do it anyway which sparked a Third Amendment case a few years back.

        The Third Amendment has to do with quartering soldiers in private houses; how does it apply to that case?
  • Comment removed based on user account deletion

    • Re: (Score:1)

      by Anonymous Coward

      Blurb is sensational saying it uses only routers, but it's not that simple: it's a number of routers carefully located and configured as transmitters and receivers, recording channel state information for 30 subchannels. 3 tx and 3 rx antennas.
      This isn't supposed to be "eerie," it's a compelling demonstration of how heavy signal processing can be used to infer body positions in a room using low cost antenna hardware. Under no circumstance did these researchers interpret body pose and position from a single

      • It's a standard 3 antenna MIMO router, which is common, using standard wifi features for CSI collection.

        Making it work for more router/room/receiver configurations is just a question of a larger training set.

    • Aluminum foil won't shield your wifi transmissions. The "tin foil hat" meme is from when cooking foil was actually tin.

      • Comment removed based on user account deletion

        • It's a good question really. I don't actually know, it's just something I was told. I assumed it was based on a minor difference in density and/or conductivity. Wikipedia [wikipedia.org] mentions that aluminum will shield most the spectrum too but critically will actually amplify frequencies around 2.6 GHz and 1.2 GHz. Clearly the real solution is to wear a actual Faraday cage over your head.

  • They must have missed the article about the VR team who had a working demo of using WiFi bandwidths for user tracking. The video showed it as effective as using cameras.

  • Surely crooks and stalkers will start using such to see who is home so they know when to strike. Are reasonably priced scramblers/jammers possible?

  • How about rodent tracking? (Score:4, Interesting)

    by bustinbrains ( 6800166 ) on Wednesday January 18, 2023 @05:29PM (#63220888)

    Could this tech eventually be used to track rodents in a residence? Knowing where rodents are hiding and their current movements would become a LOT easier if a device sifting through variances in radio signals can be pointed in a general direction and then it pinpoints the location of every critter to within an inch. A future version of the device could be a cat-like robot that just stalks rodents.

    There are a lot of people in New York City who would benefit from such a device.

    • Thermal imaging can probably already do that.

    • Wavelength of 2.4GHz is 4.9 inches. For 5GHz it is 2.4 inches. So that may limit the resolution of what can be detected reliably, although perhaps phase measurements could improve resolution. If there was a publicly available frequency to use at higher frequencies maybe that would help. WiFi doesn't go through walls all that well, but it can make it through one or three typical home drywall walls so it could perhaps detect motion and approximate location, even using 5GHz. 10-20GHz would give more preci
  • of Roe vs. Wade was, at least in part, a refutation of the right to privacy of and control over ones own body, the implications are profound.

    • Faraday cage in the walls? At least external walls so that you can use wifi within the home.

      Of course you will need some form of 4g/5g signal repeaters to have telco signals within the house. Maybe with an antenna for that outside the home, and wired to the repeater in the home.

      It's possible to work around such things, if you know what you are doing .......... and can afford the costs involved.

  • Awesome scene. Coming to a neighborhood near you: https://www.youtube.com/watch?... [youtube.com]
  • The setups used by the researchers are highly controlled with compared to environment around home. They use multiple routers and control the EM environment. But the biggest reason this wouldn't work is you have to have a set of training images along with Wi-Fi signals. So if somebody really wanted to use this method for spying they could just use the camera
  • If someone is motivated enough to see you, they'll see you, and they don't need cutting-edge gadgets to do it. Authorities or just anyone with access to the telephone switchboard could be monitoring your conversations day and night since the 1930s...but they weren't. Except for bored old women looking for gossip. And the Stasi, but hey, can't make an omelette...

  • How many fingers am I holding up?

    Good, now guess WHICH ONE.

  • ...in unauthorized sex tapes!
  • I can't get WiFi on the other side of my 4 bedroom house, but some people can get it to see through walls ?

    Whaaat ?

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