When Keyhole launches its service, EarthViewer will include 40 U.S. cities. Image data will be updated annually. Some markets with fast-growing outlying areas may be refreshed more often, Hanke added. Keyhole and its competitors gather data from firms including satellite providers, aerial photo businesses and other companies typically tapped by commercial real estate companies for similar data. The photos then can be accessed over the Internet via a subscription service.
Some companies also offer on-site installations for real estate firms.
Keyhole also plans to allow its imagery to be loaded onto handheld devices like PDAs and pocket PCs. Keyhole competitor Skyline Software Systems has offered similar applications since 1997. The company's Digital Earth application can be accessed via the Internet for a subscription-based price. Like Keyhole, Skyline offers maps. A newer competitor, GlobeXplorer , was founded in 1999.