This means Google Maps users can choose to see an overhead photograph of the area they searched for instead of a conventional graphical map. The same option is provided to users of the Google Local index of business listings.
As is possible with Google's conventional maps, users can zoom in and out of the image, as well as drag it in any direction to view cropped-out sections. When users request driving directions, Google also lays over the image a line linking the two destinations, as it does with its conventional maps.
Satellite and aerial images will be handy for a variety of users, said John Hanke, the Keyhole unit's general manager. For example, users who are visually oriented might find it easier for planning driving directions, while those in the process of moving to a new place will be able to survey the locations of house or apartments they may be considering, he said. Likewise, users in the process of booking travel will be able to scan the surroundings of available hotels, he said.
The images come from a variety of private-sector and government sources and are refreshed typically every 12-18 months, he said. They cover the continental US, as well as some cities in Canada and the Baja California, which is part of Mexico.
No voyeur's paradise
For those concerned about privacy, the service doesn't zoom in to a degree that would let a user say, identify a person or peek at a window, Hanke said.
Google sells downloadable versions of Keyhole with extra features not available on the Web site. A version for individual users costs $29 per year, while one for businesses costs $599 per year.
The version for individuals, among other things, lets the user "fly" across the areas being scanned in a video game-like experience, Hanke said. The business version has features such as measuring the size of an area and exporting the flying "movie" experience to other applications such as software for presentations, he said.
Google will continue to develop the fee-based versions, as well as the free service, because the company feels they appeal to different types of users, Hanke said.