Where's Waldo . . . and 6 billion others? | Science News

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Where's Waldo . . . and 6 billion others?

5:11pm, April 15, 2003

Scientists at Oak Ridge (Tenn.) National Laboratory have combined satellite imagery and detailed census data to develop a worldwide database that can provide estimates of the number of people located in areas on a grid that has boxes with areas of 1 square kilometer or less.

The researchers describe the LandScan database, which they say will help determine populations at risk from natural and manmade disasters, in the July Photogrammetric Engineering & Remote Sensing.

Jerome E. Dobson and his colleagues used satellite images and other geographic data to determine land characteristics, such as the slope of terrain, and the prevalence of roads and nighttime lights.

With this information, scientists can estimate the number of people located in rectangles measuring 30 arcseconds of the Earth's circumference on a side. Such cells measure 1 km on a side at the equator and become smaller as latitudes increase.

Although future versions will provide both

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