9 ms·

Identifying a person through walls from video footage, using only WiFi

195 points by lelf 7y ago

velosol 7y ago
For those wondering the bottom line, it is interesting preliminary research on a small pool and I expect will be quite interesting as it progresses. "The lab has tested their new technology on 1,488 WiFi-video pairs, drawn from a pool of eight people, and in three different behind-wall areas, and achieved an overall accuracy of 84% in correctly identifying the person behind the wall."
- anigbrowl 7y ago
  1,488 Yeah I often do exactly 62 trials with 24 combinations (eyeroll)
  - acbart 7y ago
    Wait, what the heck, why did they pick what is apparently a popular hate symbol for white supremacists? The first google result takes me to: https://www.adl.org/education/references/hate-symbols/1488 https://www.adl.org/education/references/hate-symbols/1488
  - vxNsr 7y ago
    Basically you’re saying that they selected their data to fit the hypothesis?
    - dx87 7y ago
      I think they're referencing that 1488 is used to represent neo-nazi beliefs. I don't know if they're trying to imply that that people that did the studies are neo-nazis, and selected that number of configurations and trials as an in joke.
      - anigbrowl 7y ago
        It certainly seems like an odd coincidence. Perhaps I'm jaundiced from years of monitoring the far right, but they do like such jokes and it's not like 62 is a round or otherwise aesthetically interesting number.
        deleted 7y ago
        [deleted]
        waterhouse 7y ago
        And you think some researchers at UC Santa Barbara, under a professor named "Yasamin Mostofi", are far-right and deliberately snuck in a white-supremacist reference? I have a feeling most of the researchers aren't even white... "Chitra Karanam", "Belal Korany", and "Herbert Cai" are the three Ph.D students. Well. Of course, even if all people involved were white, and even if it was a deliberate reference, as long as there's nothing other than the number, no one should get in trouble for that. Under no circumstances should researchers be worrying about the numbers they come up with. If you're doing 420 trials at 69 degrees Fahrenheit, so be it. Cf. this thread: "Six paediatric health‐care professionals were recruited to swallow a Lego head. Previous gastrointestinal surgery, inability to ingest foreign objects and aversion to searching through faecal matter were all exclusion criteria. Pre‐ingestion bowel habit was standardised by the Stool Hardness and Transit (SHAT) score. Participants ingested a Lego head, and the time taken for the object to be found in the participants stool was recorded. The primary outcome was the Found and Retrieved Time (FART) score." https://news.ycombinator.com/item?id=18519899 https://news.ycombinator.com/item?id=18519899
        anigbrowl 7y ago
        It only needs one person, and I am not suggesting anyone get in trouble but expressing my skepticism about its random nature.
        mcbits 7y ago
        It would be more interesting if the number 1,488 never appeared in any of the millions of papers containing numbers in the low-thousands range.
dvt 7y ago
Cool project, but it's hard for me to see applications here. > Can a pair of WiFi transceivers outside the house determine if the person inside the house is the same as the one in the robbery video? Questions such as this have motivated this new technology We have windows, tiny little cameras that go through walls, and we can ping cell-phones. Correct me if I'm wrong, but wouldn't all of those work better than this incredibly convoluted method?
- z3c0 7y ago
  In a practical sense, yes, there are innumerably easier methods for determining the presence of a a person within a building. On a legal basis, however, in some states it's illegal to even look over a privacy fence without a search warrant. I imagine this approach is less accounted for by lawmakers of the past.
- Johnny555 7y ago
  There's lots of applications -- how about a motion sensor to tell you when there's a person on the other side of your door -- and since it's modeled off of humans, it's immune to false signals from cars or animals. And since it could use your existing home Wifi as the source signal thus the sensor would be receive-only, it could be very battery efficient so could last a long time on battery.
- mic47 7y ago
  > We have windows, tiny little cameras that go through walls, and we can ping cell-phones. Correct me if I'm wrong, but wouldn't all of those work better than this incredibly convoluted method? This is research. Currently it's unreliable (83% is super low) and convoluted, but with more research and investments, it is possible that they would be able to make it reliable and practical.
devoply 7y ago
Can't wait this technology to make it into the hands of the US military where it will be used to justify sending a few missiles their way. Thank you for your service.
alexfromapex 7y ago
This could end up being a privacy nightmare if LEOs are allowed to use it for probable cause
- anigbrowl 7y ago
  I'm giving serious thought to throwing down money on copper paint to make a faraday cage undercoat next time I feel like a different color scheme. People today are subject to surveillance capabilities that George Orwell and the Stasi could not even have dreamt of.
  - vxNsr 7y ago
    How do you plan on having cell coverage or even WiFi inside your home?
    - evan_ 7y ago
      Microcell for cellular coverage, wifi shouldn’t be a problem since the transmitter is inside and you wouldn’t need to shield interior walls
      - kranner 7y ago
        And less interference from neighbours' Wi-Fi.
    - anigbrowl 7y ago
      Wifi works fine inside a faraday cage. If I need cell coverage I can always go outside.
    - Johnny555 7y ago
      If you're so worried about surveillance that you're willing to turn your house into a Faraday cage, why would you have an active cell phone in your house (or provide a microcell that "they" can use for their own listening devices)?
  - kspacewalk2 7y ago
spydum 7y ago
So basically gait analysis using WiFi power levels. At present requires making the user walk through a specific choke point to measure the gait, then can compare any other captured video to compare. Pretty neat!
- pg_is_a_butt 7y ago
  Also requires the user to never alter their gait to purposefully deceive such detectors.
- joe_the_user 7y ago
  When you put it that way, it seems actually like it would be hard and messy to deploy in any detail. The thing about a lot of machine learning tools is they can get better and better over a period of a decade and yet still remain undeployable - see self-driving cars. I mean, the hypothetical suspect situation would like be extremely messy and getting a clear scan to deploy this seems implausible. General purpose surveillance would probably just use cameras intended for the purpose.
- eps 7y ago
  I wish they described what it was exactly instead of mudding things up with that hiding robber example.
ayakura 7y ago
link to research paper: https://www.ece.ucsb.edu/~ymostofi/papers/MobiCom19_KoranyKaranamCaiMostofi.pdf https://www.ece.ucsb.edu/~ymostofi/papers/MobiCom19_KoranyKa...
huntermeyer 7y ago
> For instance, consider a scenario in which law enforcement has a video footage of a robbery. They suspect that the robber is hiding inside a house. Can a pair of WiFi transceivers outside the house determine if the person inside the house is the same as the one in the robbery video? Questions such as this have motivated this new technology. Goodbye 4th Amendment. Would be cool if these intelligent folks but their efforts towards improving privacy.
- dahart 7y ago
  I don’t see any reason the existence of spy tech would damage the 4th amendment. We already have spy tech (way better spy tech than this, btw), and the amendment still works to prevent (at least some) unreasonable search & seizure. This is a neat application of WiFi signals, but the accuracy is nowhere near good enough for this to reliably ID random people. I’m way more worried about online corporate surveillance that actually can ID me reliably with 100% accuracy and get a lot more info about me besides where I am, than I am of government surveillance of my walking gait through walls.
  - mlyle 7y ago
    Not to mention the posited scenario has nothing to do with the 4th amendment. If you reasonably believe a suspect is hiding in a house such that surveillance is a decent approach, you could go kick down the door. Choosing to verify first with wifi is a gentler approach.
    - deleted 7y ago
      [deleted]
- kspacewalk2 7y ago
  I don't get this attitude. If something is technologically/scientifically feasible, it will get invented, and it will get perfected and it will get used. Military drones, human cloning, designer babies, you name it. Taking the high road just means someone else will do it instead.
yummypaint 7y ago
Any thoughts on fcc compliant countermeasures? Maybe some pocket sized metalic radar reflectors to ruin the snr?
- RunningDroid 7y ago
  Chicken wire in lathe & plaster?
  - RunningDroid 7y ago
    Wetware autocorrect typo: s/lathe/lath/
  - deleted 7y ago
    [deleted]
- pg_is_a_butt 7y ago
  Always skip when committing crimes
dzhiurgis 7y ago
Strangely video that's part of article doesn't really show "3D mesh" that's extracted thru signal, just some random """signal""" GIF. While I do believe something like this is possible, the evidence of this actually working is not really convincing.
- Johnny555 7y ago
  They don't extract a 3D mesh from the signal -- this doesn't literally "see through walls". They use the 3D mesh to model how they think they signal would be modified by the person behind the wall, then they compare the received signal with their model to see if it's a match.
lgats 7y ago
If this is possible using only a pair of WiFi transmitters and decibel information, what will be possible with U1/Ultra-wideband spectrum use coming to iPhones?
- snagglegaggle 7y ago
  X-ray specs.
imhoguy 7y ago
I see potential line of Faraday's cage inspired clothing coming up soon. A Scanner Darkly like scramblesuit would be even better.
- jimpudar 7y ago
  Wouldn't that also prevent your cell phone from connecting to the network?
  - imhoguy 7y ago
    Absolutely and benefitialy, you would need just to take it out of shielded pocket to reconnect. BTW: http://tinwhiskers.net/signalobscura-the-faraday-inspired-cell-signal-blocking-scarf/ http://tinwhiskers.net/signalobscura-the-faraday-inspired-ce...
- aflag 7y ago
  Do you think a tin foil hat will actually be part of the outfit? I guess first we laughed at them, but then...
simias 7y ago
Judging by the video they achieve 83% success rate with a pool of 8 people in what looks like perfect conditions (only one person, no perturbation of any kind etc...). The video also states, rather suspiciously IMO, that "This scene on the other side is shown solely for presentation and was not used for identification". Why not show the actual footage of the experiment? >The lab has tested their new technology on 1,488 WiFi-video pairs, drawn from a pool of eight people, and in three different behind-wall areas, and achieved an overall accuracy of 84% in correctly identifying the person behind the wall. What does it mean exactly? They only need one short video and one short wifi capture to get 84% success rate? That's what the video seems to imply but I find that very hard to believe. Or maybe it's just because it's fairly easy to distinguish among 8 people (especially if they have significantly different body types) and it won't work quite as well at large. I can identify my girlfriend's footsteps in the staircase with remarkable accuracy but I can guarantee you that it won't scale to the general population. Maybe it works better than I give it credit for but they need to bring up better evidence IMO.
- Zenst 7y ago
  >What does it mean exactly? They only need one short video and one short wifi capture to get 84% success rate? Key aspects upon this are that it works by matching up their style of walking (gate), so the person needs to be moving not only in the wifi data capture, but also the video they are matching with. They use the video to extrapolate a 3D mesh model of that person walking. Then model a wifi signal upon that model and produce a signature for that person that they can then use to match up with what the wifi signal is picking up. Whilst measuring some bodies way of walking has been done many times before, this add's another way of doing that - but without the need for a camera feed. So with this approach - no they can't produce a video image of the scene behind the wall from the wifi signal(s). Remember - individuals have many unique traits, many of which we havn't tapped into yet, though as far as walking styles go - that has been done for years, this just creates another way of measuring those and matching up with other forms of data, video in this case. Other things that could be explioted this way would be for example sound - a contact mic array would allow you to (thru a wall) measure a person's heartbeat to some degree and match that up to an individual. Privacy wise, this may well traction well compared to other forms of surveillance.
jjcm 7y ago
Who knew the ministry of silly walks[1] would be a privacy measure in the future? In all seriousness, the confidence interval of this is really low - 83% among a tiny pool of individuals. It's really interesting to be sure, but the tiny amount of confidence would make it extremely unlikely to be used in the context of justice/law enforcement (then again, maybe not [2]). [1] https://www.youtube.com/watch?v=78OKaiYld1E https://www.youtube.com/watch?v=78OKaiYld1E [2] 10% false positive rate in active use: https://www.smh.com.au/national/nsw/mobile-cannabis-tests-on-drivers-gave-inaccurate-results-researchers-say-20190912-p52qm6.html https://www.smh.com.au/national/nsw/mobile-cannabis-tests-on...
newscracker 7y ago
This is quite fascinating at first glance, but if this does become a viable method for law enforcement to use, the worry is that a 82% or 83% or 89% confidence score still gives in to a huge doubt. Actions taken on this basis could be uncalled for. If the justice system gets accustomed to it and relies on such confidence levels without looking for additional corroborating evidence, it would be disastrous.
Beltiras 7y ago
Couldn't this be amped up by having at least 3 sets of Tx and Rx and get locations of moving objects? That's the dream application for LEOs, not gait recognition for which you would seldomly have data.
_russelldb 7y ago
Can this be defeated simply by wearing a long loose skirt? Robe/Kaftan/yukata etc etc?
- ovi256 7y ago
  If you sew metallic mesh that's reflecting at WiFi frequencies in the skirt, yeah, that should hide some of the gait.
  - _russelldb 7y ago
    But before I mean. They have video of a person, that person is wearing a full length wide skirt...or full body robe?
    - ovi256 7y ago
      That's basically mesh opaque to visible wavelengths. The effect would be that you can't observe limb or limb part movement inside the skirt, but only how they move and deform the skirt volume. I think that's still enough, given that gait recognition works on people in burkas or other well covering garments.
empath75 7y ago
Wouldn’t it be easier to just grab the MAC address from their phone

195 points by lelf 7y ago

For those wondering the bottom line, it is interesting preliminary research on a small pool and I expect will be quite interesting as it progresses. "The lab has tested their new technology on 1,488 WiFi-video pairs, drawn from a pool of eight people, and in three different behind-wall areas, and achieved an overall accuracy of 84% in correctly identifying the person behind the wall."

anigbrowl 7y ago
1,488 Yeah I often do exactly 62 trials with 24 combinations (eyeroll)
- acbart 7y ago
  Wait, what the heck, why did they pick what is apparently a popular hate symbol for white supremacists? The first google result takes me to: https://www.adl.org/education/references/hate-symbols/1488 https://www.adl.org/education/references/hate-symbols/1488
- vxNsr 7y ago
  Basically you’re saying that they selected their data to fit the hypothesis?
  - dx87 7y ago
    I think they're referencing that 1488 is used to represent neo-nazi beliefs. I don't know if they're trying to imply that that people that did the studies are neo-nazis, and selected that number of configurations and trials as an in joke.
    - anigbrowl 7y ago
      It certainly seems like an odd coincidence. Perhaps I'm jaundiced from years of monitoring the far right, but they do like such jokes and it's not like 62 is a round or otherwise aesthetically interesting number.
      - deleted 7y ago
        [deleted]
      - waterhouse 7y ago
        And you think some researchers at UC Santa Barbara, under a professor named "Yasamin Mostofi", are far-right and deliberately snuck in a white-supremacist reference? I have a feeling most of the researchers aren't even white... "Chitra Karanam", "Belal Korany", and "Herbert Cai" are the three Ph.D students. Well. Of course, even if all people involved were white, and even if it was a deliberate reference, as long as there's nothing other than the number, no one should get in trouble for that. Under no circumstances should researchers be worrying about the numbers they come up with. If you're doing 420 trials at 69 degrees Fahrenheit, so be it. Cf. this thread: "Six paediatric health‐care professionals were recruited to swallow a Lego head. Previous gastrointestinal surgery, inability to ingest foreign objects and aversion to searching through faecal matter were all exclusion criteria. Pre‐ingestion bowel habit was standardised by the Stool Hardness and Transit (SHAT) score. Participants ingested a Lego head, and the time taken for the object to be found in the participants stool was recorded. The primary outcome was the Found and Retrieved Time (FART) score." https://news.ycombinator.com/item?id=18519899 https://news.ycombinator.com/item?id=18519899
        anigbrowl 7y ago
        It only needs one person, and I am not suggesting anyone get in trouble but expressing my skepticism about its random nature.
      - mcbits 7y ago
        It would be more interesting if the number 1,488 never appeared in any of the millions of papers containing numbers in the low-thousands range.

dvt 7y ago

Cool project, but it's hard for me to see applications here. > Can a pair of WiFi transceivers outside the house determine if the person inside the house is the same as the one in the robbery video? Questions such as this have motivated this new technology We have windows, tiny little cameras that go through walls, and we can ping cell-phones. Correct me if I'm wrong, but wouldn't all of those work better than this incredibly convoluted method?

z3c0 7y ago
In a practical sense, yes, there are innumerably easier methods for determining the presence of a a person within a building. On a legal basis, however, in some states it's illegal to even look over a privacy fence without a search warrant. I imagine this approach is less accounted for by lawmakers of the past.
Johnny555 7y ago
There's lots of applications -- how about a motion sensor to tell you when there's a person on the other side of your door -- and since it's modeled off of humans, it's immune to false signals from cars or animals. And since it could use your existing home Wifi as the source signal thus the sensor would be receive-only, it could be very battery efficient so could last a long time on battery.
mic47 7y ago
> We have windows, tiny little cameras that go through walls, and we can ping cell-phones. Correct me if I'm wrong, but wouldn't all of those work better than this incredibly convoluted method? This is research. Currently it's unreliable (83% is super low) and convoluted, but with more research and investments, it is possible that they would be able to make it reliable and practical.

devoply 7y ago

Can't wait this technology to make it into the hands of the US military where it will be used to justify sending a few missiles their way. Thank you for your service.

alexfromapex 7y ago

This could end up being a privacy nightmare if LEOs are allowed to use it for probable cause

anigbrowl 7y ago
I'm giving serious thought to throwing down money on copper paint to make a faraday cage undercoat next time I feel like a different color scheme. People today are subject to surveillance capabilities that George Orwell and the Stasi could not even have dreamt of.
- vxNsr 7y ago
  How do you plan on having cell coverage or even WiFi inside your home?
  - evan_ 7y ago
    Microcell for cellular coverage, wifi shouldn’t be a problem since the transmitter is inside and you wouldn’t need to shield interior walls
    - kranner 7y ago
      And less interference from neighbours' Wi-Fi.
  - anigbrowl 7y ago
    Wifi works fine inside a faraday cage. If I need cell coverage I can always go outside.
  - Johnny555 7y ago
    If you're so worried about surveillance that you're willing to turn your house into a Faraday cage, why would you have an active cell phone in your house (or provide a microcell that "they" can use for their own listening devices)?
- kspacewalk2 7y ago

spydum 7y ago

So basically gait analysis using WiFi power levels. At present requires making the user walk through a specific choke point to measure the gait, then can compare any other captured video to compare. Pretty neat!

pg_is_a_butt 7y ago
Also requires the user to never alter their gait to purposefully deceive such detectors.
joe_the_user 7y ago
When you put it that way, it seems actually like it would be hard and messy to deploy in any detail. The thing about a lot of machine learning tools is they can get better and better over a period of a decade and yet still remain undeployable - see self-driving cars. I mean, the hypothetical suspect situation would like be extremely messy and getting a clear scan to deploy this seems implausible. General purpose surveillance would probably just use cameras intended for the purpose.
eps 7y ago
I wish they described what it was exactly instead of mudding things up with that hiding robber example.

ayakura 7y ago

link to research paper: https://www.ece.ucsb.edu/~ymostofi/papers/MobiCom19_KoranyKaranamCaiMostofi.pdf https://www.ece.ucsb.edu/~ymostofi/papers/MobiCom19_KoranyKa...

huntermeyer 7y ago

> For instance, consider a scenario in which law enforcement has a video footage of a robbery. They suspect that the robber is hiding inside a house. Can a pair of WiFi transceivers outside the house determine if the person inside the house is the same as the one in the robbery video? Questions such as this have motivated this new technology. Goodbye 4th Amendment. Would be cool if these intelligent folks but their efforts towards improving privacy.

dahart 7y ago
I don’t see any reason the existence of spy tech would damage the 4th amendment. We already have spy tech (way better spy tech than this, btw), and the amendment still works to prevent (at least some) unreasonable search & seizure. This is a neat application of WiFi signals, but the accuracy is nowhere near good enough for this to reliably ID random people. I’m way more worried about online corporate surveillance that actually can ID me reliably with 100% accuracy and get a lot more info about me besides where I am, than I am of government surveillance of my walking gait through walls.
- mlyle 7y ago
  Not to mention the posited scenario has nothing to do with the 4th amendment. If you reasonably believe a suspect is hiding in a house such that surveillance is a decent approach, you could go kick down the door. Choosing to verify first with wifi is a gentler approach.
  - deleted 7y ago
    [deleted]
kspacewalk2 7y ago
I don't get this attitude. If something is technologically/scientifically feasible, it will get invented, and it will get perfected and it will get used. Military drones, human cloning, designer babies, you name it. Taking the high road just means someone else will do it instead.

yummypaint 7y ago

Any thoughts on fcc compliant countermeasures? Maybe some pocket sized metalic radar reflectors to ruin the snr?

RunningDroid 7y ago
Chicken wire in lathe & plaster?
- RunningDroid 7y ago
  Wetware autocorrect typo: s/lathe/lath/
- deleted 7y ago
  [deleted]
pg_is_a_butt 7y ago
Always skip when committing crimes

dzhiurgis 7y ago

Strangely video that's part of article doesn't really show "3D mesh" that's extracted thru signal, just some random """signal""" GIF. While I do believe something like this is possible, the evidence of this actually working is not really convincing.

Johnny555 7y ago
They don't extract a 3D mesh from the signal -- this doesn't literally "see through walls". They use the 3D mesh to model how they think they signal would be modified by the person behind the wall, then they compare the received signal with their model to see if it's a match.

lgats 7y ago

If this is possible using only a pair of WiFi transmitters and decibel information, what will be possible with U1/Ultra-wideband spectrum use coming to iPhones?

snagglegaggle 7y ago
X-ray specs.

imhoguy 7y ago

I see potential line of Faraday's cage inspired clothing coming up soon. A Scanner Darkly like scramblesuit would be even better.

jimpudar 7y ago
Wouldn't that also prevent your cell phone from connecting to the network?
- imhoguy 7y ago
  Absolutely and benefitialy, you would need just to take it out of shielded pocket to reconnect. BTW: http://tinwhiskers.net/signalobscura-the-faraday-inspired-cell-signal-blocking-scarf/ http://tinwhiskers.net/signalobscura-the-faraday-inspired-ce...
aflag 7y ago
Do you think a tin foil hat will actually be part of the outfit? I guess first we laughed at them, but then...

simias 7y ago

Judging by the video they achieve 83% success rate with a pool of 8 people in what looks like perfect conditions (only one person, no perturbation of any kind etc...). The video also states, rather suspiciously IMO, that "This scene on the other side is shown solely for presentation and was not used for identification". Why not show the actual footage of the experiment? >The lab has tested their new technology on 1,488 WiFi-video pairs, drawn from a pool of eight people, and in three different behind-wall areas, and achieved an overall accuracy of 84% in correctly identifying the person behind the wall. What does it mean exactly? They only need one short video and one short wifi capture to get 84% success rate? That's what the video seems to imply but I find that very hard to believe. Or maybe it's just because it's fairly easy to distinguish among 8 people (especially if they have significantly different body types) and it won't work quite as well at large. I can identify my girlfriend's footsteps in the staircase with remarkable accuracy but I can guarantee you that it won't scale to the general population. Maybe it works better than I give it credit for but they need to bring up better evidence IMO.

Zenst 7y ago
>What does it mean exactly? They only need one short video and one short wifi capture to get 84% success rate? Key aspects upon this are that it works by matching up their style of walking (gate), so the person needs to be moving not only in the wifi data capture, but also the video they are matching with. They use the video to extrapolate a 3D mesh model of that person walking. Then model a wifi signal upon that model and produce a signature for that person that they can then use to match up with what the wifi signal is picking up. Whilst measuring some bodies way of walking has been done many times before, this add's another way of doing that - but without the need for a camera feed. So with this approach - no they can't produce a video image of the scene behind the wall from the wifi signal(s). Remember - individuals have many unique traits, many of which we havn't tapped into yet, though as far as walking styles go - that has been done for years, this just creates another way of measuring those and matching up with other forms of data, video in this case. Other things that could be explioted this way would be for example sound - a contact mic array would allow you to (thru a wall) measure a person's heartbeat to some degree and match that up to an individual. Privacy wise, this may well traction well compared to other forms of surveillance.

jjcm 7y ago

Who knew the ministry of silly walks[1] would be a privacy measure in the future? In all seriousness, the confidence interval of this is really low - 83% among a tiny pool of individuals. It's really interesting to be sure, but the tiny amount of confidence would make it extremely unlikely to be used in the context of justice/law enforcement (then again, maybe not [2]). [1] https://www.youtube.com/watch?v=78OKaiYld1E https://www.youtube.com/watch?v=78OKaiYld1E [2] 10% false positive rate in active use: https://www.smh.com.au/national/nsw/mobile-cannabis-tests-on-drivers-gave-inaccurate-results-researchers-say-20190912-p52qm6.html https://www.smh.com.au/national/nsw/mobile-cannabis-tests-on...

newscracker 7y ago

This is quite fascinating at first glance, but if this does become a viable method for law enforcement to use, the worry is that a 82% or 83% or 89% confidence score still gives in to a huge doubt. Actions taken on this basis could be uncalled for. If the justice system gets accustomed to it and relies on such confidence levels without looking for additional corroborating evidence, it would be disastrous.

Beltiras 7y ago

Couldn't this be amped up by having at least 3 sets of Tx and Rx and get locations of moving objects? That's the dream application for LEOs, not gait recognition for which you would seldomly have data.

_russelldb 7y ago

Can this be defeated simply by wearing a long loose skirt? Robe/Kaftan/yukata etc etc?

ovi256 7y ago
If you sew metallic mesh that's reflecting at WiFi frequencies in the skirt, yeah, that should hide some of the gait.
- _russelldb 7y ago
  But before I mean. They have video of a person, that person is wearing a full length wide skirt...or full body robe?
  - ovi256 7y ago
    That's basically mesh opaque to visible wavelengths. The effect would be that you can't observe limb or limb part movement inside the skirt, but only how they move and deform the skirt volume. I think that's still enough, given that gait recognition works on people in burkas or other well covering garments.

empath75 7y ago

Wouldn’t it be easier to just grab the MAC address from their phone