Slashdot Log In
Shadow Analysis Could Spot Terrorists
Posted by
kdawson
on Fri Sep 05, 2008 08:24 AM
from the made-in-the-shade dept.
from the made-in-the-shade dept.
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.
Related Stories
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
Upon deployment.... (Score:5, Insightful)
Go ahead, develop more technology, there's always around it.
Re:Upon deployment.... (Score:5, Funny)
OK students, today we practice 'Ballet of the Bombs', everyone have their 6-pack strapped on?
Parent
Re:Upon deployment.... (Score:5, Funny)
Parent
Re:Upon deployment.... (Score:5, Funny)
(Score:2, Insightful)
I never go anywhere without a six-pack and a strap-on.
Insightful?? I shudder to think what that mod considers funny.
Parent
Re:Upon deployment.... (Score:5, Funny)
Parent
Re:Upon deployment.... (Score:5, Informative)
Parent
Re:Upon deployment.... (Score:5, Informative)
Aye, well the Scots have them all beat:
University of West Scotland research reveals that a woman's gait may reveal her orgasmic ability. [physorg.com] - A new study found that trained sexologists could infer a woman's history of vaginal orgasm by observing the way she walks. The study is published in the September 2008 issue of The Journal of Sexual Medicine, the official journal of the International Society for Sexual Medicine and the International Society for the Study of Women's Sexual Health.
Combine that with satellite-based shadow analysis, and... Giggity!
Parent
Re:Upon deployment.... (Score:5, Funny)
Parent
How exact is this? (Score:5, Interesting)
Will old people at the bus stop be killed by predator drones because their walk is 95% similar to OBL's?
Parent
Re:Upon deployment.... (Score:5, Interesting)
How does it account for any type of foot, ankle, or leg injury that doesn't require crutches?
How about someone throwing a handful of rocks in the shoe to forcibly change their gait?
How about someone that is conscientious enough to change their gait at every new location?
(I cannot lay claim to these ideas myself - I read Cory Doctrow's "Little Brother" - a very good novel that is licensed under the Creative Commons model and is available at http://craphound.com/littlebrother/ [craphound.com] )
This just reeks of wasted money and more governmental control.
Parent
Yes, but that still doesn't answer his questions (Score:5, Insightful)
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.
Parent
Bullshit and strawmen? (Score:5, Insightful)
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.
Parent
Re:Upon deployment.... (Score:5, Insightful)
Actually, there is no shadow analysis. This is just one of dozens of counter-intelligence announcements meant to cause a response by the terrorists. DHS figures if terrorists are out taking dancing lessons, learning the bagpipes, practicing synchronized swimming, and growing herbs then they'll have far less time to make bombs and blow stuff up.
-Loyal
Parent
Geostationary? (Score:5, Insightful)
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.
Re:Geostationary? (Score:5, Interesting)
5-10 cm is 1985 resolution, dude. About the time they got bought by Bournes (now Recon/Optical, Inc.), engineers from Chicago Aerial Industries were bragging at MIT meetings in Chicago that we'd never know the resolution of the Keyhole series. Recon, the successor to Chicago Aerial Industries now HQ'd in Virginia, has dominated the industry ever since CAI cameras detected Soviet missiles in Cuba in October, 1962.
And from the same sources, the original Hubble "mirror flaw" occured because they shipped a Keyhole part by mistake. Not hard to believe since they built both systems. Left unsaid was how similar the Hubble/Keyhole airframes were.
23 years later, after spending gadzillion bucks inventing & perfecting adaptive/active optics and instant digital signal processing we certainly are being observed even more closely.
Go ahead, ding a Senior Citizen for trolling... I'll soon be dead anyway.
Parent
Finally, the truth! (Score:5, Funny)
I knew it! The Ministry of Silly Walks is really just a subdivision of MI6!
Defeated (Score:5, Insightful)
Defeated by a simple 2 inch lift in one shoe.
Obviously... (Score:5, Funny)
Obviously, but this isn't exactly rocket science.
Well, that's easy. (Score:5, Funny)
Just point at the screen and say "Enhance this part!" There you go. If there's something in the way, like a rock, tree, or the roof of a building, just say "Enhance it again" and you'll get all the resolution you need.
If that isn't good enough for you then maybe you could create a GUI interface using Visual Basic [youtube.com] to do the job for you.
Would TV lie to me about this kind of thing?
I did some work on this a few years back (Score:5, Interesting)
My own was using lamberts cosine law to gather angular information on leg position by the light patterns reflected off the thigh of someone walking directly towards the camera.
The problem with gait recognition is, AFIAK, it's not really been proven to be a decent biometric - i.e. I'm not sure it's really all that unique, not without measuring things at a very high resolution, which probably isn't going to be possible either from space or with the current install-base of cctv cams.
Anyway, scary stuff if it does work.
Defeating gait analysis (Score:5, Informative)
Wonderful euphemism (Score:5, Insightful)
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?
Solution in search of problem (Score:5, Insightful)
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.
Re:So if it.. (Score:5, Funny)
taste and smell..
"Excuse me,natalie portman, you have been selected for a random terrorist check, step behind the screen while our terrorism expert tastes you. "
"Does she taste like hot grits?! "
Parent
Re:So if it.. (Score:5, Funny)
So if it looks like a terrorist, talks like a terrorist, and now walks like a terrorist, it is a terrorist? We should find a way to see how they taste and smell..
I'm guessing - almonds.
Parent