
Identifying a person through walls from video footage, using only WiFi - lelf
https://techxplore.com/news/2019-10-method-enables-person-walls-candidate.html
======
simias
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.

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cgrand-net
> "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?

My understanding is that the video on the left (the one showing the other side
of the wall) is just here to illustrate what's the wifi setup senses and was
not used for identification as the whole point is to identify without
(optically) seeing what's on the other side.

~~~
simias
Oooh, okay, that makes more sense. Thank you for clearing that up.

Still, that leaves the problem of the "pool of eight people" and how this
technology would work in less controlled environments.

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huntermeyer
> 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.

~~~
kspacewalk2
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.

~~~
ssss11
That mentality is a race to the bottom which ends in no humanity

~~~
ikeyany
All of the countries that did not invest heavily in their militaries no longer
exist.

~~~
dragonwriter
Iceland is a figment of my imagination?

~~~
sroussey
And Costa Rica?

~~~
hobofan
And most individual countries in Europe?

~~~
chronic71819
> Iceland is a figment of my imagination?

> And Costa Rica?

> And most individual countries in Europe?

All of these countries, for practical purposes, do not exist.

They do not have influence on the world stage. They may as well be China,
considering how easy these countries will bend to Chinese money.

So either you develop the surveillance tech, or you must look the other way
when China develops it. If you disagree, your economy will be ruined.

------
spydum
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!

~~~
joe_the_user
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.

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jjcm
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...](https://www.smh.com.au/national/nsw/mobile-cannabis-tests-on-drivers-
gave-inaccurate-results-researchers-say-20190912-p52qm6.html)

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

~~~
anigbrowl
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
How do you plan on having cell coverage or even WiFi inside your home?

~~~
evan_
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
And less interference from neighbours' Wi-Fi.

------
velosol
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
_1,488_

Yeah I often do exactly 62 trials with 24 combinations (eyeroll)

~~~
vxNsr
Basically you’re saying that they selected their data to fit the hypothesis?

~~~
dx87
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
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.

~~~
waterhouse
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
It only needs one person, and I am not suggesting anyone get in trouble but
expressing my skepticism about its random nature.

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dzhiurgis
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
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.

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

~~~
RunningDroid
Chicken wire in lathe & plaster?

~~~
RunningDroid
Wetware autocorrect typo: s/lathe/lath/

------
Beltiras
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.

------
dvt
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
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.

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newscracker
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.

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

~~~
jimpudar
Wouldn't that also prevent your cell phone from connecting to the network?

~~~
imhoguy
Absolutely and benefitialy, you would need just to take it out of shielded
pocket to reconnect. BTW: [http://tinwhiskers.net/signalobscura-the-faraday-
inspired-ce...](http://tinwhiskers.net/signalobscura-the-faraday-inspired-
cell-signal-blocking-scarf/)

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

~~~
ovi256
If you sew metallic mesh that's reflecting at WiFi frequencies in the skirt,
yeah, that should hide some of the gait.

~~~
_russelldb
But before I mean. They have video of a person, that person is wearing a full
length wide skirt...or full body robe?

~~~
ovi256
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.

------
lgats
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
X-ray specs.

------
ayakura
link to research paper:
[https://www.ece.ucsb.edu/~ymostofi/papers/MobiCom19_KoranyKa...](https://www.ece.ucsb.edu/~ymostofi/papers/MobiCom19_KoranyKaranamCaiMostofi.pdf)

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empath75
Wouldn’t it be easier to just grab the MAC address from their phone

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devoply
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.

