An army of amateur online cartographers is embarking on what could prove the most concerted effort to map India since the British Empire tackled the task.

Fed up with getting lost in Bangalore, the sprawling centre of India’s IT industry, a team of engineers from Google, the net’s largest search engine, has devised a tool to let web users annotate and amend satellite images to produce useful maps.

Within weeks of its launch, tens of thousands of Indians have filled in details of their cities, towns and villages, many of them previously blank spaces in even the most up-to-date atlases. The technology, which is being extended to other “information-deficient” regions, such as Africa, is widely viewed as the future of map-making and is on course to be worth billions for Google in advertising revenues.

Lalitesh Katragadda, the creator of Google Map Maker, told The Times: “We’ve seen a fantastic emotional interplay emerge. People want to map their favourite restaurants, their old school classrooms. This is going to fill in a big piece of the geo-web puzzle.” In particular, Google says it is targeting “hyper-growth countries” such as India, where maps are changing daily.

A host of websites already allow users to amend online maps, and some bloggers have accused Google of apeing nonprofit projects such as OpenStreetMap. org, which place fewer restrictions on how collected information can be used.

Google reckons, however, that its enormous online reach gives it a better chance of hitting critical mass than its competitors. Dr Katragadda says its map service has already achieved what his team calls “the genesis effect”, the point at which the wealth of data captured attracts a rush of users to the map site, who in turn plug in more information.

For all of Google’s high-tech terminology, the ambitions underpinning its mapping project seek to echo those of the young British adventurers who strove to chart India in the 18th and 19th centuries. Above all, the East India Company sought to collect information to maximise what James Rennell, the Surveyor General of Bengal, called “the advantages that may be derived from our territorial acquisitions” or, in other words, the commercial profits that could be wrought from India. Today, map data combined with advertising in a form that can be beamed to mobile phones is regarded as an area potentially worth a similarly impressive fortune.

Last year Tele Atlas, a digital maps supplier, was bought for $2.1 billion (£1.2 billion) by TomTom, the satellite navigation maker, despite Tele Atlas not having turned an annual profit in a decade.

TomTom later said it would buy data such as the location of businesses from Google to overlay on to its digital maps, since trying to gather such information by itself would cost “millions”. In India, Google is having its own users do the job for it.

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