They don’t know it, but people who use Google’s online maps may be getting directions from Richard Hintz.
Mr. Hintz, a 62-year-old engineer who lives in Berkeley, Calif., has tweaked the locations of more than 200 business listings and points of interest in cities across the state, sliding an on-screen place marker down the block here, moving another one across the street there. Farther afield, he has mapped parts of Cambodia and Laos, where he likes to go on motorcycle trips.
Mr. Hintz said these acts of geo-volunteerism were motivated in part by self-interest: he wants to know where he’s going. But “it has this added attraction that it helps others,” he said.
Mr. Hintz is a foot soldier in an army of volunteer cartographers who are logging every detail of neighborhoods near and far into online atlases. From Petaluma to Peshawar, these amateurs are arming themselves with GPS devices and easy-to-use software to create digital maps where none were available before, or fixing mistakes and adding information to existing ones.
Like contributors to Wikipedia before them, they are democratizing a field that used to be the exclusive domain of professionals and specialists. And the information they gather is becoming increasingly valuable commercially.
Google, for example, sees maps playing a growing strategic role in its business, especially as people use cellphones to find places to visit, shop and eat. It needs reliable data about the locations of businesses and other destinations.
“The way you get that data is having users precisely locate things,” said John Hanke, a vice president of product management who oversees Google’s mapping efforts.
People have been contributing information to digital maps for some time, building displays of crime statistics or apartment rentals. Now they are creating and editing the underlying maps of streets, highways, rivers and coastlines.
“It is a huge shift,” said Michael F. Goodchild, a professor of geography at the University of California, Santa Barbara. “This is putting mapping where it should be, which is the hands of local people who know an area well.”
That is changing the dynamics of an industry that has been dominated by a handful of digital mapping companies like Tele Atlas and Navteq.
Google is increasingly bypassing those traditional map providers. It has relied on volunteers to create digital maps of 140 countries, including India, Pakistan and the Philippines, that are more complete than many maps created professionally.
Last month Google dropped Tele Atlas data from its United States maps, choosing to rely instead on government data and other sources, including updates from users.
“They have coverage in areas that the big mapping guys don’t have,” said Mike Dobson, a mapping industry consultant who once worked at Rand McNally. “It has the opportunity to cause a lot of disruption in these industries.”
Some people think map data is so valuable that it should be free. OpenStreetMap, a nonprofit group whose mission is to make free maps that can be reused by anyone, has some 180,000 contributors who have mapped many countries in varying levels of detail. The maps are used on a White House Web site that tracks community service opportunities and in many iPhone applications, among other places.
Another collaborative project called WikiMapia is creating its own annotated maps, layered on top of Google’s.
Traditional mapmakers are seeking to adapt by tapping their own citizen cartographers. Tele Atlas, which TomTom bought last year for $4.3 billion, now uses feedback from users of TomTom’s navigation devices to update its maps.
But Tele Atlas says its customers, who might be in delivery trucks or emergency vehicles, can’t rely fully on community-created maps, any more than historians can rely on Wikipedia.
“Most of our customers expect a level of due diligence and quality that is way more than what a community is going to put together,” said Patrick McDevitt, vice president of global engineering at Tele Atlas.
Defenders of the amateur approach point out that professionally created maps often have errors and can be slow to add road closures and other updates. Google has moderators who try to verify the accuracy of users’ changes, unless they are very minor, while OpenStreetMap relies on its members to police changes.
“As far as we can tell so far, these new sources are as accurate as the traditional ones,” Professor Goodchild said.
Contributors to OpenStreetMap have turned the task into a social activity. Last month, a group of some 200 volunteers in Atlanta braved the wind and drizzle to collect map data across the city. Armed with GPS devices, cameras and paper maps of neighborhoods, they added missing alleys, public art, restaurants and hotels.
John L. Kittle Jr., a 55-year-old engineer, was one participant. In the past, Mr. Kittle has corrected street names in Atlanta and improved the map for his home town of Decatur, Ga. Recently an acquaintance mentioned that she lived in a new condo development, and Mr. Kittle added it to the map.
“Seeing an error on a map is the kind of thing that gnaws at me,” he said. “By being able to fix it, I feel like the world is a better place in a very small but measurable way.”
Mr. Kittle said contributing to a project where anyone can freely use the mapping data was important to him. Others, like Mr. Hintz, said they could make a greater contribution through Google, whose maps are widely used.
Some of the most remarkable efforts of amateur map makers are in countries where few, if any, digital maps existed. Google first tested a tool called Map Maker in India, where people immediately began tracing and labeling roads and buildings on top of satellite images provided by Google.
When Google released the tool more broadly last year, Faraz Ahmad, a 26-year-old programmer from Pakistan who lives in Glasgow, took one look at the map of India and decided he did not want to see his homeland out-mapped by its traditional rival. So he began mapping Pakistan in his free time, using information from friends, family and existing maps. Mr. Ahmad is now the top contributor to Map Maker, logging more than 41,000 changes.
Maps are political, of course, and community-edited maps can set off conflicts. When Mr. Ahmad tried to work on the part of Kashmir that is administered by Pakistan, he found that Map Maker wouldn’t allow it. He said his contributions were finally accepted by the Map Maker team, which is led by engineers based in India, but only after a long e-mail exchange.
At his request, Google is now preventing further changes to the region, after people in India tried to make it part of their country, Mr. Ahmad said. “Whenever you have a Pakistani and an Indian doing something together, there is a political discussion or dispute.”
A Google spokeswoman, Elaine Filadelfo, said Google sometimes blocked changes to contentious areas “with an eye to avoiding back-and-forth editing.”