Watch your step! The Pentagon is developing a radar-based device that can identify people by the way they walk, for use in a new antiterrorist surveillance system.
Operating on the theory that an individual's walk is as unique as a signature, the Pentagon has financed a research project at the Georgia Institute of Technology that has been 80 to 95 percent successful in identifying people.
If the Defense Advanced Research Projects Agency, or DARPA, orders a prototype, the individual "gait signatures" of people could become part of the data to be linked together in a vast surveillance system the Pentagon agency calls Total Information Awareness.
That system already has raised privacy alarms on both ends of the political spectrum, and Congress in February barred its use against American citizens without further review.
Nevertheless, US government documents show that scores of major defense contractors and prominent universities applied last year for the first research contracts to design and build the surveillance and analysis system.
DARPA is the federal agency that helped develop the Internet as a research tool for universities and government contractors. Its newest project is massive by any measure.
In its advice to contractors, DARPA declared, "The amounts of data that will need to be stored and accessed will be unprecedented, measured in petabytes."
One petabyte would dwarf most existing databases; it's roughly equal to 50 times the Library of Congress, which holds more than 18 million books.
Conceived and managed by retired Admiral John Poindexter, the TIA surveillance system is based on his theory that "terrorists must engage in certain transactions to coordinate and conduct attacks against Americans, and these transactions form patterns that may be detectable."
DARPA said the goal is to draw conclusions and predictions about terrorists from databases that record such transactions as passport applications, visas, work permits, driver's licenses, car rentals, airline ticket purchases, arrests or reports of suspicious activities.
TIA is an effort to design breakthrough software "for treating these databases as a virtual, centralized grand database" capable of being quickly mined by counterintelligence officers even though the data will be held in many places, many languages and many formats, DARPA documents say.
Poindexter's plan would integrate some projects DARPA has been working on for several years, including research headed by Gene Greneker at Georgia Tech. At a cost of less than US$1 million over the past three years, he has been aiming a 0.3m2 radar dish at 100 test volunteers to record how they walk.
Elsewhere at Georgia Tech, DARPA is funding researchers to use video cameras and computers to try to develop distinctive gait signatures.
"One of the nice things about radar is we see through bad weather, darkness, even a heavy robe shrouding the legs, and video cameras can't," Greneker said in an interview. "At 600 feet [183m] we can do quite well," he said.
And the target doesn't have to be doing a Michael Jackson moonwalk to be distinctive because the radar detects small frequency shifts in the reflected signal off legs, arms and the torso as they move in a combination of different speeds and directions.
"There's a signature that's somewhat unique to the individual," Greneker said. "We've demonstrated proof of this concept."