Everybody, take a look at this:
Kirstie
I know what you did...
If you're up to no good, expect an unhappy ending
TURNING a script into a film is a Hollywood speciality but the "inverse
Hollywood problem" of turning a film into a script is a lot harder,
especially
for a computer. But now there's a system that can analyse video footage and
generate a script that describes what the people in it are doing. It should
appeal to employers who want to track the activities of their staff, legal
or
otherwise, in offices and other workplaces.
Computer systems can already recognise images of objects and people, but
they find it much tougher to classify what people are doing. From a video of
someone picking up a briefcase, say, a computer may be able to recognise
the briefcase and the person. But the fact that the human is holding a
briefcase is much more difficult to detect.
Now Muburak Shah and Douglas Ayers at the University of Central Florida
in Orlando have developed a system that can tell whether an object has
been grasped and lifted, by tracking the trajectories of people's hands and
fingers.
With a single camera observing an office, the system can spot actions such
as making a phone call or opening cabinets and drawers. It also monitors
whether people carry objects out of the room. The computer then produces
a script describing these actions. "Analysing the trajectories of hands and
fingers is the hardest part, but our accuracy is close to 100 per cent,"
says
Shah.
A computer that has been given information about who owns which objects
should be able to spot when someone is using other people's phones or
computers, or if they are stealing objects from the room.
The system is more invasive than current surveillance methods, says Barry
Steinhardt, an expert on computer privacy at the American Civil Liberties
Union in New York. Employers can already monitor e-mails, phone
conversations and computer keystrokes, but until now analysing video
footage has been tedious and time-consuming.
More at: Image and Vision Computing (vol 19, p 833)
Justin Mullins
3 November 2001
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