The digital geographers

The internet: Detailed digital maps of the world are in widespread use. They are compiled using both high-tech and low-tech methods

IT IS a damp, overcast Monday morning in Watford, an undistinguished town north of London that seems to offer little to the casual visitor. But one man is eagerly snapping photographs. In fact, he is working with six high-resolution cameras, all of which are attached to the roof of the car in which he is being driven. He sits in the passenger seat with a keyboard on his lap, tapping occasionally and muttering into a microphone. A computer screen built into the dashboard shows the car’s progress as a luminous dot travelling across a map of the town. The man is a geographic analyst for NAVTEQ, one of a small group of companies that are creating new, digital maps of the world.

Each keystroke he makes denotes a feature in the outside world that is added to the map displayed on the screen. New details are also recorded in audio form. Once the journey is finished, the analyst can also pick out new details while watching a video playback. All this information is transferred from a server in the car’s boot to NAVTEQ’s database.

Companies such as NAVTEQ and its rivals, which include Tele Atlas and Microsoft, always start a new map by going to trusted sources such as local governments or mapping organisations. This information can be corroborated using aerial or satellite photography. Only when these sources are exhausted do they switch to the more expensive process of gathering data themselves. The digital maps they create are used mostly by motorists in rich countries. But the same companies are now creating maps of the developing world, which is requiring them to do things in somewhat different ways.

A geographic analyst in India would probably have deserted his vehicle, finding it impractical to manoeuvre on the country’s crowded urban streets. Instead, he would go on foot and use a pen to annotate a map printed on paper, a technique abandoned by his Western counterparts a decade ago. Official mapmaking in some poor countries is far from comprehensive, leaving the likes of NAVTEQ or Tele Atlas to generate the most accurate maps available.

The type of data that must be gathered also varies. Navigation in wealthy Western markets generally requires gathering the information that is of most interest to motorists. But lower levels of car ownership in poor countries makes such information less relevant. Instead, the proliferation of mobile phones in countries such as China or India, many of which incorporate satellite-positioning chips, may make pedestrian navigation more relevant for local customers. Mapmakers are more likely to spend time hanging around bus stations collecting timetables, or finding the quickest route, which is not always the most direct one, from a city’s railway station to its main shopping street. All this information has to be constantly refreshed, sometimes several times a year.

To reduce the cost of sending staff on such reconnaissance trips, mapping companies are asking their customers to do more of the work. Tele Atlas, for example, gathers data from users of satellite-navigation systems made by TomTom, a firm based in the Netherlands. Drivers can report errors and suggest new features, or can agree to submit data passively: the TomTom device automatically logs their vehicle’s position, leaving a trail where it has travelled. It is then possible to calculate the vehicle’s direction and speed, which can help identify the class of road on which it is travelling. Altitude measurements mean the road’s gradient can be determined. Other information can also be deduced. If a lot of cars all seem to be driving across what was thought to be a ploughed field, for example, then it is likely that a new road has been built. Such detective work keeps the company’s mapping database up to date.

In some parts of the world, however, mapmaking relies heavily on voluntary contributions. Google’s Map Maker service, for example, makes up for the lack of map data for much of the world by asking volunteers to provide it. Among its contributors is Tim Akinbo, a Nigerian software developer who got involved with the project last year. He has mapped recognisable features in Lagos, where he lives, as well as his home town of Jos. Churches, banks, office buildings and cinemas all feature on his map.

His working method is relatively simple. His mobile phone does not have satellite positioning, but he can use it to call up Google Maps, see what is on the map in a particular area and make a note of things to add. He then goes online when he gets home to add new features.

Why should people freely give up their time to improve local maps? Mr Akinbo explains that local businesses could use Map Maker to alert potential customers to their existence. “They will be contributing to a tool from which other people can benefit, as well as themselves,” he explains. With enough volunteers a useful map can be created without the need for fancy camera-toting cars.

Source of Information : The Economist 2009-09-05