North Chelmsford, MA —One of the toughest challenges with the Web is figuring out how to send large files back and forth over skinny Internet access lines so engineers can see each others' drawings. Now, two new web sites have found solutions, both for a similar application—posting searchable, high-resolution topographic maps.
At TopoZone (www.topozone.com ), you can search every US Geological Survey (USGS) scale map in the United States—including 1:100,000, 1:63,360, 1:25,000, and 1:24,000. You use this site without knowing it when you visit popular sites like MapQuest.
And at TerraServer (San Francisco, CA, http://terraserver.microsoft.com/ ), viewers can sort through aerial, topographic, and satellite images of any place in the continental United States and around the world. The aerial photos present spooky, grainy, black and white images of many places you've only seen from ground level. Alcatraz is here, alongside the Statue of Liberty and the Houston Astrodome. There's the Kennedy Space Center, Fermi National Laboratory, and the Hoover Dam.
Oh, and by the way, your three-bedroom ranch house on Elm Street, USA, is visible here, too.
Terraserver began as a joint research project between Aerial Images Inc. (Raleigh, NC), Microsoft (Redmond, WA), Compaq (Houston, TX), and the USGS. Aerial wanted to sell imagery online, and Microsoft was looking for a way to show off its new database software.
Message to Microsoft: Be careful what you wish for—it may come true. It turns out that these images take up a staggering amount of space. For a host server, Microsoft uses a Compaq ProLiant 8500 running eight 550MHz Intel processors, 4 GB of RAM, and 140 hard drives holding 9.1GB each. For software, the 8500 is running Windows 2000 Data Center edition, Microsoft's SQL Server™2000. And that's only for the USGS digitized topographical maps, which soak up 762 GB of data, stored in 68 million records.
A second database for the USGS aerial photography uses a Compaq AlphaServer 8400 running Windows NT 4.0 Enterprise Edition, and SQL Server 7.0. That database has 1,796 GB of data stored in 206 million records. And a third database for the satellite images also uses SQL Server 7.0. If you put all this data into a paper atlas, you'd have 2,000 volumes of 500 pages each, Microsoft says.
To squeeze all this info over phone lines into your living room, TerraServer chops the enormous files into 200-pixel-by-200-pixel tiles, and compresses the result into a JPEG file format so your browser can read it.
TopoZone faced a similar challenge when it bought 58,938 topographical maps from the USGS, all at 250 dpi, enough to cover the entire country. But a longtime complaint of hikers is that these maps do not line up perfectly along the edges, so TopoZone's first job was to fit the jigsaw together.
"We created a seamless mosaic of the entire country, then went through and chopped it up into small tiles," explains company president Bill Everett.
Nineteen million tiles, to be exact. The information fills up a 600GB SQL database, running on Dell servers at the company's Charlestown, MA, data center. But unless they produced postage stamp-sized maps, squeezing this rich data through a standard modem connection would take too long. So TopoZone samples the resolution down from 250 to 125 dpi.
"It's the whole issue of how dense you want your data," Everett says. "We have to maintain the quality of the image, and balance that with the speed of download access, all in a map size that means something." The maps are all free on the web site today, and TopoZone is launching a family of products this year that will allow customers to customize the size, shape, and resolution of the maps they need.
Applications for the technology may include: faster file transfers of engineering drawings, environmental groups planning natural resources management, state agencies monitoring polluting companies, and even children preparing school reports.
And of course, you can find out all sorts of neat stuff about your home or office. For instance, the decimal latitude here at Design News is 42.356543, and longitude is 71.181394. Go ahead and take a look at us—I'll look out the window and wave.
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