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> 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.



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> 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.


Thanks for the interesting answer, lots of things I want to google now! :D

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

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...


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