
China can apparently now identify citizens based on the way they walk - tzury
https://techcrunch.com/2018/11/07/china-can-apparently-now-identify-citizens-based-on-the-way-they-walk/
======
cimi_
Setting who wants to do this aside in order to avoid the constant 'X is worse
than Y' arguments.

I don't think it's unreasonable to assume that in a near future we will have
cameras that can do much more than identification on a massive scale. It may
be easy to track things like how stressed, healthy, sober etc. people are
without their consent or without them even noticing. And this would be
_precise_ , not speculative like the current online tracking.

Would you live comfortably in this world? Would you build this?

~~~
InclinedPlane
Yup. Think about how you can recognize your friends without even seeing their
face, by the way they walk, what they wear, how tall they are, and other
contextual clues. Computers will be able to do all of that. Also think about
other things that only computers with massive amounts of data will be able to
do. Computers will be able to enumerate your wardrobe, your possessions.
They'll be able to figure out most of the books you've read or own. They'll
know where you work, what your schedule is, where you shop, what you do for
fun, when you take vacations and where. They'll be able to learn all of this
even if you don't freely give all this information up through social media
posts and what-have-you by following you in the background of other stuff or
through other "feeds". Imagine how much easier it is to identify someone in a
picture or a video if you can pull in "big data" context which narrows down
the possible/likely people who could be in that location at that time (wearing
those clothes, doing that activity, within a given weight/height range, etc,
etc, etc.)

We don't really know what the feasible computational and data limits are here,
the potential (and likelihood, I think) is that they are much, much lower than
where we would like them to be. In the near future something very close to
ubiquitous surveillance is very likely to be the norm. And that has all sorts
of chilling implications. If systems can keep track of where you are and what
you're doing most hours of most days then that opens up a lot of questions in
terms of free expression, political organizing, civil disobedience, etc.

~~~
elorant
Sound like advertiser's heaven. Sign me out please.

------
yodon
I made a couple trips to the South Pole in grad school. Down there you were
either a scientist in a red parka, black insulated pants, and white boots or
support staff in brown carharts. No part of the body could be seen at a
distance and even the gloves were standard issue.

What constantly amazed me was how you could see someone walking a quarter mile
away and instantly know exactly who it was.

The South Pole is a smaller population than China so I'd be worried about
false positives (probably mostly within families as kids learn to stand and
walk like their parents and have similar dimensions when fully grown) but I
suspect it's actually a pretty robust identification technique.

~~~
taneq
> The South Pole is a smaller population than China so I'd be worried about
> false positives

Even if the false positive rate is really low, it's still a problem. All of
these dragnet-style things mess with your priors. In a traditional
investigation, the police have a handful of suspects and then gather evidence.
Circumstantial evidence showing that the chances are 1 in 1000 that this one
_of the five suspects_ was not the culprit is pretty convincing, and probably
enough to convict.

Cast a dragnet over a city of 1 million, and suddenly that same 1-in-1000
error rate will be giving you 1000 innocent people who, under the old system,
are 'guilty beyond reasonable doubt'. They've been pre-selected to look pretty
frikkin' bad regardless of whether they're guilty, which means any one of them
will have a hell of a time proving their innocence.

~~~
erikpukinskis
I suspect there’s quite a bit of case law on what probability of false
positives is acceptable?

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r-bryan
In Cory Doctorow's _Little Brother_, some characters would put pebbles in
their shoes so gait-recognizers wouldn't recognize them.

~~~
on_and_off
That's what real life spies do too

edit : a source :
[https://www.youtube.com/watch?v=JASUsVY5YJ8](https://www.youtube.com/watch?v=JASUsVY5YJ8)

~~~
Choco31415
The relevant time stamps 4:39-5:02.

Former CIA Chief: "Changing the way that you walk requires some amendment to
what you're doing. You're going to need a physical apparatus to make you walk
differently. You can't possibly say, okay, now I'm going to limp. To change my
walk, I put a little piece of gravel in my shoe, just a little thing that
pinches my toe, and it changes my walk whether I want to or not. You can put a
bandage around a knee, something that restricts you, will change your walk."

------
nabla9
1\. Gait detector is functional.

2\. Countermeasure: use stone in the shoe, tape and other things to fool the
gait detector.

3\. Counter-countermeasure: detect artificial gaits. Everyone unrecognized
with artificial gait is person of interest.

~~~
dpwm
4\. Counter-counter-countermeasure: wheels.

~~~
nabla9
5\. You don't have enough social credit for wheels.

------
otto2
This will cause people to start walking on the street in the same way as
Fremen in Frank Herbert's Dune, by varying frequency and step length in order
not to attract a (government) worm.

~~~
cirgue
I was thinking more Ministry of Silly Walks.

~~~
Semiapies
Combine it with Morrison's _The Invisibles_.

"Big Brother is watching. Learn to move indescribably."

------
YeGoblynQueenne
So, my understanding is that the machine vision technologies discussed in this
article don't really work that well, at least not once deployed in the real
world, outside of "the lab" and away from the controlled conditions of a
scientific experiment reported in a research paper.

I wonder, then- do the authorities of the various countries (by far not just
China) who make use of this kind of technology know how little they add to
their ability to spy on their citizens? If they know- do they use it anyway
just so that lucrative contracts can be signed and money exchange hands? Do
they (also?) figure that the fear of being identified by all-seeing, all-
knowing cameras will keep the population in the straight and narrow, even if
the cameras are blind and dumb as bricks, in practice?

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Tade0
My Bachelor's (of engineering) thesis was in biometrics and if there's one
thing I remember from the seminars it's that gait along with typing rhythm and
voice are these modalities that pop up every now and then only to disappear
after a while after their proponents figure out that it's no use.

These modalities simply don't carry enough information to reliably identify
anyone.

Facial recognition works best when you need the subject to be unaware that
they are being identified.

~~~
informatimago
You don't necessarily need to identify one amongst 1.3 billion. (requiring 30
bits of information out of the gait!)

The context is a crowd of about 100 (10 - 1000), in which you are tracking a
few percent, and you need to keep "eyes" on an individual, discriminating
amongst a few others that have crossed is path.

That said, I'd agree that it looks difficult to help distinguish individuals
in a trained team.

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coliveira
This is not new, and is not unique to China. Any country with intelligence
units, like the US, is using data mining to identify and control their
citizens. It has become fashionable lately to imply that China is the only
country doing these things, or somehow doing it in larger scale. Has everyone
forgotten what Snowden revealed?

~~~
bsamuels
I dont remember anything in the snowden docs about the NSA trying to track the
movement of all american citizens.

Comparing what the NSA does to what China does is like comparing the treatment
of women in the US and Saudi Arabia

~~~
coliveira
Of course, Snowden was only able to review what he saw 5 years ago or more.
Why you have any doubts that the NSA, with ample resources to track and
control, would use techniques similar to what the Chinese do? Do we really
need another Snowden to realize this obvious fact?

~~~
vokep
Because while sure they may be working on any sinister form of control
possible, the NSA has to do it in secret, which makes it a bit harder to
trample on rights. In China it isn't secret, its just the way things are.

------
trainingaccount
Can they tell if I'm a women's man, no time to talk?

------
jandrese
I'm curious what the false positive rate is on this technology. It seems like
a very noisy source to do correlations from.

~~~
diydsp
I'm about to walk out the door so I can't look up papers, but I'm going to
guess that it's based as much on dynamics as actual proportions of limbs. I
would estimate the number of features to be on the scale of 2000-2010 era
facial recognition. Dynamics would increase the number of dimensions, making
it possible to separate two people with nearly identical features.

However, I do agree that inferring the proportions from video imagery at
various angles and with various items of clothing is going to be challenging
due to systemic distortion, e.g. inferring incorrect angle due to clothing.

~~~
cxseven
If they blanket an area with cameras, as China does, they can use multiple
vantage points to get more accurate measurements and, when a positive ID is
made, they can persistently track that person crossing from one field of view
to another.

I think the main advantage of gait analysis (or limb proportion measurement)
is that it will encourage a more efficient, decentralized computation that
first distills the observed data into a fingerprint that can be more easily
transmitted over a wire to a massive database for matching, rather than the
alternatives of either replicating that database or transmitting raw, high-
bandwidth data.

Besides limb measurements, they could also use last known location, residence,
and vehicle ownership information to increase the certainty of loose matches.

------
geitir
One of the books I read when I was younger that got me into programming is
Little Brother by Cory Doctorow. In the book, the high school they attend has
cameras that identify students by measuring gait. The characters in the book
put gravel in their shoes to throw the tech off when cutting class.

------
mhb
If this is all out in the open in China and many Chinese people even approve
of it, wouldn't it be more efficient to have everyone wear ID tags of some
kind?

~~~
apexalpha
Because those are easier to fake than your face or way of walking. And you
want to monitor the people who'd be inclined to fake this.

------
wwarner
I'm skeptical, especially of the surveillance claims. If you already know who
you're looking for and you have lots of footage of that person, you might be
able to train your system to pick up that person's gait from new footage. But
that's a far cry from being able to "identify anyone" by their gait, i.e. set
up lots of cameras around the city and track individuals coming and going.

There are already amazing airborne camera systems that track the motion of
every license plate in a city, and even that isn't the same as tracking every
car's movement because you still have to know which license plate to follow --
you just can't care about all movement of all cars. I suppose someone will say
that you can store all movement in a database, but I'll wager that's just not
worth anywhere near the cost. Your computing power would be much better spent
on computing large primes.

Anyway, it's a cool sci-fi movie premise. You can see the murderer shaving off
his mustache, burning off his own fingerprints and then knee-capping himself
to avoid detection.

~~~
nindalf
> you just can't care about all movement of all cars

Of course we can. For each license plate encountered by CCTV or cop cars,
store a tuple of (timestamp, coordinates). This won't require much disk space,
so that's not a concern. Later, it is easy to answer questions like "what
places was this car seen and when?" and "which cars were in this vicinity at
this time?"

~~~
wwarner
Well, let's test your claim. Say there are 1 million cars in a city. Say your
camera system covers 300 square miles (to handle nyc). The question is how
long would it take to scan the images from a single moment and capture all
license plates. At 5 seconds per plate, that's 57 days. Plenty of time to
commit a crime and escape without detection. And again, you could've been
doing something useful like capturing some large prime numbers, in order to
break the encryption of someone who is actually trying to hide something.

~~~
somebodythere
Why would it take 5 seconds a plate? They could as well station a licence
plate reader at each intersection, and update a key-value store with a given
plate's last seen location whenever one is spotted. O(1).

~~~
wwarner
Parallelization you say? 5 seconds is constant time, and a pretty optimistic
one. How many license plates are visible from any given intersection in my
town, NYC? Somewhere between 5 and 50. There is always motion, so what should
the frame rate be? You probably can't commit much of a crime in 15 seconds,
but you can drive an 8th of a mile (at 30 mph), about two intersections. So
let's settle on a frame rate of 5 seconds. You still won't have much precision
with cameras only at each intersection, so let's put them 10 feet apart, and
let's have 4 at each point. Honestly, that's a minimum. At 10 feet apart, for
NYCs 6074 miles of road, that's 12,828,288 computerized cameras. That's about
$12B. And I still bet that the error rate will be too high to be useful.

I'm not arguing that it will never be possible, I'm arguing that the original
claim, and the mass surveillance that make people nervous, is not happening
today.

------
d0ne
This isn't new. Gait recognition has been in use for well over a decade.

------
eganist
Mitigation strategies discussed in an unrelated (but relevant) conversation
between WIRED and Jonna Mendez -
[https://www.youtube.com/watch?v=JASUsVY5YJ8&t=278](https://www.youtube.com/watch?v=JASUsVY5YJ8&t=278)
(if you're not auto-jumped, find 4:38 in the video)

~~~
Erlich_Bachman
A url with &t= pretty much always auto-jumps.

------
80mph
Anyone who's heavily near-sighted knows this technique. In college, my dorm
bathroom was quite a distance from my room. At night, I would remove my
contact lenses, and upon returning I would always identify certain people by
their style of walking, or their posture.

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cooperellis
UK has been doing this for decades:
[https://www.youtube.com/watch?v=iV2ViNJFZC8](https://www.youtube.com/watch?v=iV2ViNJFZC8)

~~~
superfrank
So have casinos.

I was really into the idea of card counting when I was in high school (over 10
years ago) and remember coming across multiple sources that claimed casinos
did this as part of their arsenal to detect people who've been blackballed.

------
resters
Surely gait analysis is part of the US arsenal as well. It's unique like a
fingerprint and is used extensively by equestrian teams, etc., to detect shoe
and health issues early to protect the investment in the horse. Many relevant
health problems are visible early on as a change in the horse's gait.

It can be done with an accelerometer or a camera, and probably other kinds of
sensors.

It could also be used for early diagnosis in humans, but is cost prohibitive
for human preventative care use.

------
pasbesoin
Remember a decade or so ago when the U.S. military was icing Middle Eastern
"terr'ist" targets based upon gait analysis?

Well, now it's you. And also, once again, brought to "the world" by China.
(Maybe they'll sell it along side of or as an add-on to their Great Firewall
turnkey systems.)

I remember viewing a few of those old video segments (drone- and plane-based
platforms) and feeling pretty nervous.

------
lozenge
...says some company.

Yeah right. The sensitivity/specificity requirements for this to be useful
would be insanely difficult or impossible to reach.

~~~
ei8htyfi5e
The US government has had this forever. This is why they train you at the farm
to put a pebble in your shoe if you’re trying to evade detection so your gait
changes. It is most certainly not impossible.

~~~
LitFan
For others that aren't aware, "The Farm" refers to a CIA training facility at
Camp Peary.

[https://en.wikipedia.org/wiki/Camp_Peary](https://en.wikipedia.org/wiki/Camp_Peary)

------
subcosmos
Gait analysis has been around for a LONG time. I saw papers 15 years ago from
labs here in the states.

------
eiaoa
How well does gait analysis work against gait-disguise techniques like putting
a pebble in your show as described in this video?

[https://www.youtube.com/watch?v=JASUsVY5YJ8](https://www.youtube.com/watch?v=JASUsVY5YJ8)

------
arcaster
Fake crutches or wheelchairs could also be an interesting foil to this method
of surveillance?

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cronix
We should all start skipping in public instead of walking, because we're
happy.

~~~
PavlovsCat
So.. happy..

> _the kinds of questions that began to present themselves were just.. the
> questions themselves were ugly and I didn 't want to know the answers. It's
> like banging on a door, you knock on a door, and the door opens slightly and
> behind that door it's dark and there's loud noises coming like there's wild
> animals in there or something. And you peer into the darknees and you can't
> see what's there but you can hear all this ugly stuff.. do you want to step
> into that room? No way, you just sorta back out quietly, pull the door shut
> behind you, and walk away from it._

\-- Bill Ehrhart (
[https://www.youtube.com/watch?v=tixOyiR8B-8](https://www.youtube.com/watch?v=tixOyiR8B-8)
)

~~~
OG_BME
He was my history teacher in Highschool. He was (and still is) an inspiring
orator and incredibly talented poet. His perspective is invaluable and has
already proven to be timeless.

------
hobbes78
Amazing that nobody has so far mentioned "Mission Impossible Rogue Nation"!
There's a scene where Benji has to pass a corridor where people are identified
by the way they walk!

------
donpdonp

      [Scanning]
      Subject: Woman's man
      Time to talk: None.

------
echevil
I remember this being a research topic while I was in grad school more than 10
years ago. Like face recognition, it is nothing unique and is being researched
by plenty of people

------
brohee
Is this defeated by the stone in shoe gait changing technique?

------
arcaster
Time for some IR emitting / reflecting pants!

~~~
biglenny
curious, how would this prevent being captured on camera? isn't visible light
used?

~~~
TomMarius
If the pants reflect whole spectrum, then it should be reasonably obscured
from cameras. I think GP did not mean mere IR reflectiveness.

------
EGreg
I wonder how hard it would be to fool them by walking differently. Are there
parameters you can’t change much?

------
harveywi
The Segway will finally be vindicated.

------
m3kw9
They gonna combine this with facial to get better accuracy

------
geggam
There was a science fiction book who talked about putting a rock in your shoe
to change your gait and avoid detection.

What was it ?

~~~
ctoth
Little Brother, Cory Doctorow. Of course then you just train a network to map
between pebbled and unpebbled gaits and run that on any failed matches. So...

~~~
ctoth
Actually Double Star did this first back in ... 1954? I loved that book when I
first read it.

