Magazine "NewScientist" 3 October 2009

"NewScientist" 3 October 2009

Virtual cities get real bustle

WHILE virtual globes such as Google Earth or Microsoft Visual Earth provide great bird's-eye views of urban landscapes, they show ghost towns - empty streets free of traffic or people.
Now a system that can draw on real-time video from traffic and surveillance cameras, and weather sensors, is set to change that. It fills virtual towns with cars and people and could even let online spectators zoom in on live sports events.
Computer scientists at Georgia Institute of Technology in Atlanta use video feeds from cameras around their city. Their augmented version of Google Earth incorporates sports scenes, traffic flows, the march of pedestrians and weather.
The system looks out for specific categories of moving objects in a video feed. Any vehicle moving along a street is classified as a car and replaced with a randomly chosen 3D car model. Pedestrians are replaced with human figures animated with stock motion-capture data to make them walk.
Although surveillance cameras are used, no one's privacy is at stake because the models obscure identifying details such as a car's colour and licence plates, says Kihwan Kim, who led the research.
"Every moving object is rendered symbolically,"says Kim.
Sports action can be recreated with less regard to privacy, using multiple camera views to create 3D models of the players.