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Online volunteers help assess storm damage
06 September 2005

San Francisco, USA: On Friday afternoon, Leonard Sprague, a general contractor in Gainesville, Florida, saw the electronic plea.

"I hope someone can help," a person using the name ZuluOne wrote to an online bulletin board. "I am trying to get a current overlay for the area around 2203 Curcor Court in Gulfport, Miss."

Sprague knew that "current overlay" meant a bird's-eye view. And an altruistic impulse combined with an urge to play with a new technology propelled him into action. Using his personal computer, he superimposed a freshly available posthurricane aerial photograph over a prehurricane image of the same neighborhood. After 15 minutes, he had an answer.

"Actually, it looks like your house looks pretty good," he told ZuluOne by e-mail. "Unfortunately, it doesn't look so good for some of your neighbors."

In the aftermath of Hurricane Katrina, hundreds of displaced residents and their relatives - along with people like Sprague - have turned to the Internet for information about a home feared damaged or destroyed. Many are using Google Earth, a program available at the Google Web site that lets users zoom in on any address for an aerial view drawn from a database of satellite photos.

By the end of last week, a grass-roots effort had identified scores of posthurricane images, determined the geographical coordinates and visual landmarks to enable their integration into the Google Earth program, and posted them to a Google Earth bulletin board, where ZuluOne turned for help.

Most of the images originated with the Remote Sensing Division of the National Oceanic and Atmospheric Administration, which has been posting them to its Web site ( since last Wednesday.

Taking inspiration from the online volunteers, Google, the National Aeronautics and Space Administration and Carnegie Mellon University had by Saturday night made the effort more formal, incorporating nearly 4,000 posthurricane images into the Google Earth database (at for public use.

Mike Aslaksen, acting chief of the National Oceanic and Atmospheric Administration Remote Sensing Division, said that while it took a week to process and make public images taken of the World Trade Center after the terrorist attacks of Sept. 11, 2001, the posthurricane images have been available within 24 hours.

They are not satellite photos but aerial images taken from a Cessna Citation jet. Still, they can be readily patched into the Google Earth database as overlays.

The images are not crystal clear, and if an area appears to be flooded, it is hard to tell how deep the water is. But the photographic overlays give a sense of a home, street or neighborhood's condition.

"People who have a reason to be personally concerned with what's happening there are motivated to do it," John Hanke, a general manager who is in charge of the Google Earth service, said on Sunday. Yet many who have no particular personal connection to the hurricane's devastation joined the effort.

Douglas Hillman, a disc jockey and dance instructor who lives near Chicago, created about 80 overlays. He said he was fascinated by Google Earth and also interested in "the results of a natural disaster, in the way people react to it, and also in the technology used to cover it."

Kathryn Cramer, a science fiction editor in Pleasantville, New York, whose Web site ( has served as a clearinghouse for overlay information, said the effort started early last week when she and a few others wondered about the exact location of a levee break and created an overlay using a photo from the news media.

"We were getting a lot of decontextualized disaster photos that didn't give you a real understanding of what was happening," she said.

In a related online collaboration, at, people are plastering a Google street map with electronic pushpins marked with information like "casino boats destroyed" and "minor wind damage."

The National Oceanic and Atmospheric Administration's images are helping the U.S. Army Corps of Engineers to assess levee damage, Aslaksen said, and the agency has used them to determine shoreline changes that might pose a risk, and to see if piers or vessels have sunk. But he said he welcomed the unofficial use.

Aslaksen, whose e-mail address is on the agency's Web site, said he had received nearly a thousand e-mail messages from people seeking information on the condition of their homes. He tries to respond to all of them, he said.

Cramer said she had been able to help nearly two dozen people looking for information about the status of their homes. "I've been thanked more in the last 48 hours than ever in my life," she said Friday.