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Shadow Analysis Could Spot Terrorists
Hugh Pickens writes "An engineer at Jet Propulsion Labs says it should be possible to identify people from the way they walk — a technique called gait analysis, whose power lies in the fact that a person's walking style is very hard to disguise. Adrian Stoica has written software that recognizes human movement in aerial and satellite video footage by isolating moving shadows and using data on the time of day and the camera angle to correct shadows that are elongated or foreshortened. In tests on footage shot from the sixth floor of a building, Stoica says his software was indeed able to extract useful gait data. Extending the idea to satellites could prove trickier, though. Space imaging expert Bhupendra Jasani at King's College London says geostationary satellites simply don't have the resolution to provide useful detail. 'I find it hard to believe they could apply this technique from space,' says Jasani." Comments on the article speculate on the maximum resolution possible from KH-11 and KH-12 spy satellites.
Go ahead, develop more technology, there's always around it.
Who puts a spysat in geostationary orbit? It's way too high, you'd need a telescope that dwarfs Hubble to get a decent view. You put spysats in the lowest orbit you can get away with, and you make sure that you have enough of them that any target of interest will be covered frequently enough for your purposes.
Real Daleks don't climb stairs - they level the building.
Defeated by a simple 2 inch lift in one shoe.
I like how yet again ``spotting terrorists'' is an euphemism for ``spotting everyone else, too''. I habitually substitute ``spotting YOU'' and honestly think of all the good it would do.
Yes, there's useful stuff in there, but again only if those watching you can be trusted. This has been said often enough before and still people score cheap headlines with the same fallacy.
Anybody spot the shadow of a flying pig yet?
So... um, you've got a "terrorist" under tight enough surveillance that you can build a "gait profile", but you're not arresting or just outright executing them?
Admittedly, I support this effort. Once complete, the DHS can take its rightful place as the Ministry of Funny Names and Walks.
c.
Log in or piss off.
Yes, but that still doesn't answer his objections.
Let's say you've got nothing to hide, are on the database, then you get an abcess in your foot. I had one, for example, thanks to some retarded shoes which did that much damage and it got infected. Next thing I knew, my walking style could belong in a "ministry of funny walks" sketch, except for me it was more painful than funny.
Would I suddenly be outside the database, and thus a suspect, in that scenario? Or what if they entered a criminal in the database when he had a similar injury, and then I have a similar injury two years later and suddenly I look like the re-appearance of Abdallah ibn Jihad, wanted for arson, genocide and jay-walking in East Bumfuckistan and Elbonia? (Made up name, btw. Means IIRC slave of Allah, son of jihad, or enough to get your average anti-terrrist spook get his panties in a knot by itself.)
It's not like you can choose when you'll have such an injury.
What is the degree of confidence in such an identification, anyway? How fine you can slice a gait and still leave room for normal daily variations? (E.g., account for stuff like today I'm feeling chippy and walk a lot livelier, while yesterday was a shitty day and my walk probably reflected that. E.g., today I walk on grass in the woods, yesterday I was walking on wet concrete, and a month ago I was walking on sand at the beach.) As they say, "if you're one in a million, there are 6000 exactly like you." Will it be able to positively identify said Abdallah ibn Jihad, even when he's walking uphill through the snow with a pebble in his boot, or will it be more like "it's one of 6000 people, one of which is Abdallah ibn Jihad"? Again, that's the number if it could positively and unerringly distinguish between one million different gaits.
A polar bear is a cartesian bear after a coordinate transform.
Bullshit and strawmen, whether intentional or not. The objections to false positives have more to do with statistics, than with slippery slopes or anything else.
E.g., let's say I have a system which can look at photos from the security cameras, and tell you if a face or gait in the crowd matches a terrorist profile with 99% accuracy. (Which is actually a lot higher than what most of these snake oil systems get.) The problem in that case isn't that it lets 1% of the terrorists go. It's that it also creates 1% false positives out of people who aren't, for just one terrorist's photo. Apply that to just one airport, say the JFK, with its almost 60,000 passengers per day. If you get exactly one photo of each passenger, that's 600 false positives per day, in just one airport, for just one terrorist. But more likely you'll have everyone caught by several cameras during their trip to the airport, so the number multiplies accordingly.
Now feed it a database of several tens of thousands of known criminals, suspects, etc, and watch the number of false positives explode. Given that accuracy, just 100 photos are enough to match a majority of the passengers at one point or another.
At some point you can simply swamp the security with false positives, to the point where it's worse than useless.
And it's not just a hypothetical scenario, it's what airport security people themselves have said about previous trials with face recognition system. That they're crap and worse than useless. Would you accuse those too of being paranoid and slippery-slope types, or just accept that they probably know their job enough to know when a gizmo isn't helping it?
So basically spare me the bullshit about "nirvana fallacies" and "paranoid liberals". Learn what the real problem is, before talking out the arse about.
A polar bear is a cartesian bear after a coordinate transform.