Google Inc. on Monday released the latest upgrades to the mapping tools that rank among the company's biggest success outside the Internet-leading search engine that steers much of the Web's traffic.

The improvements include a major expansion of the satellite imagery included in Google's three-dimensional software for touring Earth.

The Mountain View, Calif.-based company said four times more land will be covered in the latest version of its free Google Earth software, enabling about one-third of the world's population to obtain an aerial view of their homes and neighborhood.

The software also is being offered in German, Spanish, French and Italian. The computer coding for the first time will work on Linux operating platforms, a breakthrough likely to broaden the product's appeal.

More than 100 million people have downloaded Google Earth software since it was offered a year ago, according to figures released by the company for the first time Monday.

Meanwhile, Google's online mapping service for finding directions and locating businesses has emerged as a major challenger to the longtime leaders in the category, AOL's Mapquest and Yahoo Inc.

Google Maps attracted 26 million U.S. visitors in May to rank third behind Mapquest at 43.5 million visitors and Yahoo at 26.1 million, according to Nielsen/NetRatings Inc. The traffic at Google's mapping service tripled during the past year while the volume of visitors at Mapquest and Yahoo rose by less than 20 percent, Nielsen/NetRatings said.

Google CEO Eric Schmidt hailed the company's mapping products as "one of the defining opportunities around search."

For all its inroads in mapping, Google still hasn't provided a clear road map for making money from the products — much to the dismay of Wall Street analysts.

Google took a small step toward addressing that concern Monday by announcing it will license usage of its online maps to businesses and government agencies that want to customize the service. The licenses, expected to begin at about $10,000 annually, will include support from Google's engineering staff.

The online maps already have enabled programmers to create Web sites that draw upon independent databases to graphically illustrate information about everything from local crime statistics to apartments available for rent in specific neighborhoods.

Google estimates about 30,000 of these mapping hybrids, known as "mashups," have been created in the past year. Despite the licensing plans, Google emphasized it plans to improve its application programming interface to make it easier to create even more mapping mashups.

Google hosted more than 200 Web developers at its headquarters Monday to trumpet its upgrades.