From left: Evaristo Sa/Agence France-Presse — Getty Images; Mat Bisher; Olivier Maire/Google, via Bloomberg News

Google just introduced a series of updated maps for 11 countries, with added information on things like ferry routes, parks, landmarks, and the layouts of universities and airports. It’s a nice achievement. What is really interesting is how Google did it, and what kind of signal they are sending to other tech companies getting into mobile maps, like Apple, Microsoft and Amazon

Google added much of the information through in-house information sources, through a project it calls “Ground Truth.” The idea is that if Google can own the geographic data, instead of purchasing it from others, it can produce maps that are more reliable. That is one reason Google’s cars have driven over five million miles, why it now has hikers, bicyclists and snowmobilers among its employees, and why it has established the indoor layouts of over 10,000 buildings in the United States and Japan (and just added a few in London). The mapmakers at Google feel the only way to know the facts is to get them themselves.

“The challenge of using multiple sources of information is conflation,” said Brian McClendon , the head of Google Earth and Maps. “There is no way to mix the best of one company’s product with the best of another.” By owning all of the information, he says, Google can more readily check the quality of the information it is getting, and subject it to Google-type computer analysis using things like computer vision, machine learning or GPS data, as well as humans checking some data.

Google also counts on input from other humans, including what Mr. McClendon said were “hundreds of thousands of users providing corrections to our information.” Some 800,000 outside software developers add information about things like the store they’re trying to advertise. “It’s the third-party data that makes this really good,” he said.

Ground Truth has been inside Google for a while, and is almost certainly working on more than the hiking trails of Croatia, the Czech Republic, Greece, Ireland, Italy, Lesotho, Macau, Portugal, San Marino, Singapore and the Vatican City. Google clearly wants to possess its own data, which it thinks it can both check and update, for every part of the Earth.

This is, aside from an impressive internal expense, a clear shot at differentiating Google from other companies hoping to get into the mobile maps business. Google is effectively saying to to its competitors (like Apple): These are the kind of expenses you’ll have – and by the way, you’ll spend years getting data we’ve already got.

Maps matter enormously, as people are carrying the Internet with them everywhere on mobile devices. A map on a phone or tablet is the intersection of the physical and virtual worlds, providing not just location information to both the user and the map provider, but also giving both parties valuable details on shopping, travel and other behavior. If, like all these companies, you want to lead in a world of Internet-empowered mobile devices, you want to own this information.

Of course, the other companies might try to get their map information from the fast-growing open-source map project called OpenStreetView. Mr. McClendon said, however, that this was one case where many contributors did not necessarily produce better results, since they were working from different standards. “Merging data from multiple sources of truth is hard,” he said, “and mapping is the best example of that.”