This story is from the category Sensors
Date posted: 14/04/2008
Tracking people's every move using buildings packed with motion sensors is more effective than CCTV, and less invasive to privacy, say researchers who tried the technique on their own colleagues.
"We want to have a god's eye view of the entire space," says Yuri Ivanov of the Mitsubishi Electric Research Laboratories (MERL), who led the project with colleague Christopher Wren.
As digital video cameras get cheaper and smaller, CCTV systems are becoming more common. But as well as raising privacy concerns, Ivanov and Wren say, the footage is difficult to search through or interpret quickly.
As an alternative, the two researchers used arrays of small, cheap motion detectors to watch over people instead, with their officemates as guinea pigs. They fitted their 3000 square metre office building with an array of 215 simple detectors placed along the hallways at 2-metre intervals.
The detectors collect much less information than the cameras. "It's not going to catch you picking your nose. You can only tell that some person went by," Wren explains, "maybe this is better than living under thousands of cameras."
But the motion-detector system still collects a lot of information. To find unusual or interesting patterns in the data, the researchers developed software to display movements of people around the building on a map in real time.
The system also includes a handful of cameras, at selected spots in the building. Footage of passers by can be used to identify people, who can then be tracked around the building using the motion sensor data.
Users can select a certain path on the map ? for example from the office drinks machine to the front door ? to call up motion and video data from the path at a particular time and reveal who used the route. "A target audience for this was security," says Ivanov, "but that's not the only use."
Data collected during a fire evacuation drill revealed that almost everyone in the building left through one exit; the two other doors nearby went largely unused. Understanding how people use spaces like this could help improve safety, they argue.
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