3D maps let travellers take virtual city tours -

location based services

The latest online mapping tool lets users take a virtual wander through cities. The Virtual Earth mapping software from Microsoft has been updated to include photo-realistic three-dimensional models of real buildings and other structures.
Previously, the software contained only aerial photos. These were linked together so that viewers could explore an area from above. Now, for the first time, they can explore the landscape in 3D as well.
"This gives you a whole other perspective on what is there," says Virtual Earth chief architect Gur Kimchi, based in Washington State, US. "Suddenly I can see the front of a building. A lot of this was invisible before."
Kimchi adds that exploring an area in 3D, before visiting it for real could help minimise the chances of getting lost. "This is basically the end of the paper map," he claims.
Street images
The new 3D version of Virtual Earth is currently available for the following US cities: San Francisco, Seattle, Boston, Philadelphia, Los Angeles, Las Vegas, Baltimore, Dallas-Fort Worth, Atlanta, Denver, Detroit, San Jose, Phoenix and Houston. But Microsoft says it will expand to more than 100 cities internationally by the summer of 2007.
To build their 3D models, Microsoft researchers travelled around these cities in cars and planes capturing many images in rapid succession. These were automatically stamped with GPS co-ordinates. The images overlap by 90%, to ensure that each building is captured from multiple different angles. Each virtual cityscape requires approximately 10 million photos.
Software was then used to combine the images and GPS data to generate a 3D picture of each city, complete with real-life texture and colour. No matter where a user chooses to look, the landscape can be rendered for that viewpoint.
Grey boxes
Google offers a rival product, called Google Earth, which also provides 3D models of buildings, but these are smooth grey boxes that do not resemble real structures.
Alex Daley of the Virtual Earth business unit says 3D cities could hopefully open up new business opportunities. For example, the buildings could someday act as virtual real estate for advertisers, he suggests.
These virtual billboards could show different ads, depending on what the user is searching for and could even follow them around if they zoom past too quickly, Daley says.