3 ms·

> gait detection is already good enough (I believe?) to uniquely identify individuals. Gait is one of those modalities that gets rediscovered every decade only

by Tade0 3y ago

> gait detection is already good enough (I believe?) to uniquely identify individuals. Gait is one of those modalities that gets rediscovered every decade only to, again, yield no results. There's just too much noise and variability over time for it to qualify for broader use. It's much easier to get a detailed image of a person's iris from 100m.

ethanbond 3y ago
Interesting! I thought it was effectively “already here” despite not being deployed much/at all. Surely the value of gait over iris would be that you don’t need ridiculously specialized sensors right? Can use (hypothetically, I guess) a bunch of CCTV sending that’s already out there.
- Tade0 3y ago
  Iris sensors are just NIR cameras illuminated by a maximum of three different frequencies. Samsung used to put them in their phones and they seem to have been using just one frequency.
  - ethanbond 3y ago
    Right but those are not installed on every corner and store in every western city like standard “gait-sensing” cameras are.
    - Tade0 3y ago
      Actually, most of the 24/7 surveillance cameras that I've seen already include a ring of NIR diodes for night vision and a sufficiently close photo from one would suffice. Even better: the wavelengths used are in the range of 700-900nm, which, as indicated by my smartphone camera picking up the 850nm diodes in my Leap Motion controller, are within the range of off-the-shelf camera sensors. For a decent image you need the iris to span 70 pixels. A Full HD camera probably won't cut it, but a 4k one installed at the entrance of a building might well be scanning irises and we wouldn't even know it.
4ggr0 3y ago
> It's much easier to get a detailed image of a person's iris from 100m. Seriously? That sounds insane, wow. I mean, an iris is like 1cm wide, can you really get a detailed image from 100m away, while the person is walking, looking around, blinking etc.? EDIT: I mean in the context of surveillance, I can imagine that a dedicated photographer could get such a picture with a fancy camera, but we're talking about 24/7 video surveillance.
- Tade0 3y ago
  > I mean, an iris is like 1cm wide, can you really get a detailed image from 100m away, while the person is walking, looking around, blinking etc.? I assumed there would be an appropriate setup for that. In any case systems collecting iris data en masse from 6m were available a decade ago. Ultimately it's just a photo in near infrared, nothing fancy. The whole reason why this even works is that the iris as a modality has an unrivaled 240+ bits of entropy, so even partial or blurred images yield enough information to identify a person(requiring 60bits at most). On top of that it's an extremely stable feature. Shabrat Gula was famously identified after almost 20 years, despite being a child when her photo was taken.
  - 4ggr0 3y ago
    Thanks for the interesting answer, lots of things I want to google now! :D
    - Tade0 3y ago
      If you want to learn more, I recommend a paper by John Daugman - inventor of the encoding system used to store and verify iris data: https://www.robots.ox.ac.uk/~az/lectures/est/iris.pdf https://www.robots.ox.ac.uk/~az/lectures/est/iris.pdf By far the largest database of irises is the one created by India’s Unique Identification Authority, with more than a billion people enrolled: https://www.irisid.com/indian-national-identity-program-tops-one-billion-enrollees-2/ https://www.irisid.com/indian-national-identity-program-tops...

by Tade0 3y ago

ethanbond 3y ago

Interesting! I thought it was effectively “already here” despite not being deployed much/at all. Surely the value of gait over iris would be that you don’t need ridiculously specialized sensors right? Can use (hypothetically, I guess) a bunch of CCTV sending that’s already out there.

Tade0 3y ago
Iris sensors are just NIR cameras illuminated by a maximum of three different frequencies. Samsung used to put them in their phones and they seem to have been using just one frequency.
- ethanbond 3y ago
  Right but those are not installed on every corner and store in every western city like standard “gait-sensing” cameras are.
  - Tade0 3y ago
    Actually, most of the 24/7 surveillance cameras that I've seen already include a ring of NIR diodes for night vision and a sufficiently close photo from one would suffice. Even better: the wavelengths used are in the range of 700-900nm, which, as indicated by my smartphone camera picking up the 850nm diodes in my Leap Motion controller, are within the range of off-the-shelf camera sensors. For a decent image you need the iris to span 70 pixels. A Full HD camera probably won't cut it, but a 4k one installed at the entrance of a building might well be scanning irises and we wouldn't even know it.

4ggr0 3y ago

> It's much easier to get a detailed image of a person's iris from 100m. Seriously? That sounds insane, wow. I mean, an iris is like 1cm wide, can you really get a detailed image from 100m away, while the person is walking, looking around, blinking etc.? EDIT: I mean in the context of surveillance, I can imagine that a dedicated photographer could get such a picture with a fancy camera, but we're talking about 24/7 video surveillance.

Tade0 3y ago
> I mean, an iris is like 1cm wide, can you really get a detailed image from 100m away, while the person is walking, looking around, blinking etc.? I assumed there would be an appropriate setup for that. In any case systems collecting iris data en masse from 6m were available a decade ago. Ultimately it's just a photo in near infrared, nothing fancy. The whole reason why this even works is that the iris as a modality has an unrivaled 240+ bits of entropy, so even partial or blurred images yield enough information to identify a person(requiring 60bits at most). On top of that it's an extremely stable feature. Shabrat Gula was famously identified after almost 20 years, despite being a child when her photo was taken.
- 4ggr0 3y ago
  Thanks for the interesting answer, lots of things I want to google now! :D
  - Tade0 3y ago
    If you want to learn more, I recommend a paper by John Daugman - inventor of the encoding system used to store and verify iris data: https://www.robots.ox.ac.uk/~az/lectures/est/iris.pdf https://www.robots.ox.ac.uk/~az/lectures/est/iris.pdf By far the largest database of irises is the one created by India’s Unique Identification Authority, with more than a billion people enrolled: https://www.irisid.com/indian-national-identity-program-tops-one-billion-enrollees-2/ https://www.irisid.com/indian-national-identity-program-tops...