Virtual reconstructions of real cities are giving town planners and architects a clearer picture of the potential impact of future designs.
Computer scientists at the University of Arkansas in the US have developed a technique for rapidly constructing accurate 3D models of real cities using a unique combination of information. This includes satellite imagery, mapping data, building records and images captured from low-flying aircraft. Textures are also recorded using handheld digital cameras.
The researchers used the technique to build a 3D model of the city of Fayetteville in northwest Arkansas, which is experiencing rapid metropolitan growth. By adding models of planned building works to the 3D model, and then importing everything into the mapping program Google Earth, they are able to see exactly how these designs would impact on the landscape.
To construct their model of Fayetteville, the researchers used "oblique" aircraft imagery captured by a US company called Pictometry, and laser-based range-finding measurements taken from the ground.
Aircraft imagery
Malcolm Williamson, at the university's Centre for Advanced Spatial Technologies (CAST), who led the project, says the aircraft imagery was particularly useful for building the 3D maps quickly. Pictometry's Electronic Field Study software made it possible to automatically calculate the measurements of buildings from the aerial images.
"That really was a big key to building accurate models," he told New Scientist. "Measurements are theoretically possible through the use of high-density aerial LiDAR, but the Pictometry photography greatly increases the likelihood of being able to see and measure what is needed."
His team imported detailed architectural models of planned buildings to create a realistic representation of the future cityscapes. "We received CAD [Computer Aided Design] models from several different developers who have had new developments already approved," he says.
The Arkansas team's efforts are being tested by Sketchup, a company specialising in 3D modelling tools, which was acquired by Google in March 2006. Google now provides Sketchup as a free tool for users to build virtual structures, which can be imported into Google Earth. Williamson says free programs like these could eventually let ordinary citizens explore their city and contribute to planning schemes.
Information sharing
"It's an interesting application," says Michael Batty, an expert on mapping at University College London's Centre for Advanced Spatial Analysis (CASA) in the UK. "But it's one of many."
Batty's own group is building a 3D model of London using some of the same types of information. He says the ability to import models into Google Earth is particularly useful for sharing information.
Steve Coast, a UK mapping expert and founder of OpenStreetMap, a community-driven mapping project, says 3D modelling could be particularly useful for urban development. "Its cool stuff," he told New Scientist. "Lots of people are trying to make money out of it for city planning."
However, Coast questions whether the increased speed of modelling justifies cost of obtaining oblique imagery using aircraft. "Photographing the building from the air rather than the ground is a bit quicker but it's no breakthrough," he says.
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