The easiest way to see what’s on offer is through sites like Ogleearth.com and Gearthblog.com. They have news and screenshots, and links to files that create the overlays for Google Earth. You click to download overlays to your computer. Then, when Google Earth is running, you choose the overlays you want displayed. John Hanke of Google showed me a few examples, which ranged from the fanciful to the highly practical.
On the practical side is an overlay from Caltrans, the agency responsible for California’s freeways. When you display this data within Google Earth, it shows congestion conditions every mile or so along freeways in the state’s major cities. Clusters of red, orange, yellow, or green dots show you where traffic is moving and where it is jammed; any dot you click on tells the average speed of cars passing that point. A WiFi overlay shows the nearest available commercial hot spots. On a skiing overlay, you can click a blue snowflake symbol by major resorts and get detailed slope information and a link to the mountain’s Web site. An aviation site called FBOWeb.com offers a free demonstration showing the trajectories airliners are taking toward several major airports; by using the tilted view you can “watch” planes as they descend over Boston Harbor or through the Los Angeles basin for landing. You can display as many of these varied overlays as you choose, clicking on a check box to turn them on or off.
Less practical, but often more delightful, creations continue to proliferate. An overlay from Blogwise.com shows who is writing a blog in your city—or in Buenos Aires or Beijing—with a link to each blog. Another shows bird migration patterns. One called South 3.1 shows the route of Ernest Shackleton’s doomed Endurance mission to Antarctica, with photos and log entries matched to their locations. Another, covering the Mount Everest area, maps the course of a 2003 Everest expedition with aerial photos so sharp you can see individual tents. The Google Earth Community overlay has Wikipedia-style notes on interesting buildings and historic sites.
Perhaps the most open-ended potential involves Google Earth’s interaction with Flickr, the photo-sharing site run by Yahoo. More than 75 million photos have been stored at Flickr, many of them tagged by location—“Paris, Arc de Triomphe”—or “geotagged” with GPS coordinates. People pay to post these pictures, as a handy way to store files that can clog hard drives and to keep them all in one place; viewing access is generally free. Using the Flickr overlay, which works through a site called Geobloggers, you can see any available photos of the place you’re looking at. For instance, when displayed in addition to the Everest overlay, Flickr brings up pictures people have taken at the summit. When I’m looking at my neighborhood, I see Flickr photos of trees that were blown down two years ago in a hurricane. New shots pour into Flickr each day, and to similar sites like Panoramio.com, founded by two young Spaniards, which lets users easily link their photos to specific sites.
Google Earth is far less powerful than “geographic information systems,” or GIS. These are complex and often expensive programs that match economic, demographic, environmental, and other data to satellite views of particular locations. A county government might use GIS to combine data on population density, fire risks, and traffic patterns to find the right location for a firehouse. Businesses use it to decide where to place distribution centers or new stores. Scientists use it to track environmental trends.
But according to Jack Dangermond, founder and president of the world’s leading GIS company, ESRI of Redlands, California, the free services available under Google Earth will increase the public’s use of geographically linked information, for-pay and free alike. “There’s no way to connect a professional data set to Google Earth, so in a sense it is pretty thin,” he said. “But because it is spellbinding to customers, it can only build awareness of geography. And if this exposure makes citizens more spatially literate, they can accept more of their information this way and visualize more about their local situations.” Many governments already use GIS to let citizens see public data, from the residences of registered sex offenders to the tax assessments of buildings, homes, and lots. Within a year or two, he said, standard Web browsers will allow citizens to “fly” through this data or see it in 3D, using features like Google Earth’s.
“Honestly, I have no idea where this is going in the long run,” John Hanke of Google told me. “Ten years ago, this technology was the exclusive province of the U.S. intelligence community. Five years ago, it cost $14,000 for a single satellite image. Now there’s free, global high-resolution imagery.” The most significant use of the technology so far, he said, has been to provide “maps for places where they had no previous maps.” He read from a newspaper story about the headman of a Kurdish village who was using a Google Earth printout to plan the village’s rebuilding. “This is really inspiring to me,” Hanke said. “It’s the sort of thing that we thought might happen as this information is released and democratized.”
Fooling around with this program and its overlays has put a few more hours on my computer total. These hours seem better spent than most.