Volunteer "citizen cartographers" are aiming to take on the likes of Google Maps and Ordnance Survey by creating a free open source wiki-style map of the planet.
The OpenStreetMap (OSM) mapping data is collected by volunteers using GPS devices to record their movements as they drive, cycle or walk along all the roads in a particular area.
OSM was started two years ago by Steve Coast because of the legal and technical restrictions on the use of other maps such as Google and OS.
Coast said: "This data is freely available. Google buys commercially restricted data. It can't make that available for free."
Coast's gripe is that in most countries mapping is done by government agencies which make money from that data by selling it back to businesses and the public, apart from the US where it has to be made available for free.
OSM relies on volunteers to collect and upload the GPS data that creates the maps. There are more than 3,600 contributors doing around 50 uploads per day and OSM also holds regular "mapping parties" where people descend on a particular area to map it over the course of a weekend.
Recent areas that have been mapped by volunteers include the Isle of Wight, the county of Rutland, the Surrey Hills and urban areas such as Bath and Reading. Once the raw GPS data is uploaded it can also be edited wiki-style by other users, who can add info such as street names.
Coast said: "Allowing people to edit it over the web is just the obvious thing to do."
OSM claims it will have the UK mapped by the middle of 2008 "if not sooner" and it is also making inroads into Europe where parts of cities such as Copenhagen have been mapped.
Coast said: "The idea is to do the whole planet. There will be a free map of the planet available. It's going to happen."
OSM has also been attracting interest from commercial users and London-based estate agency Nestoria has started using OSM mapping data for its online property-search service in the Isle of Wight.
Access to postcode data is a more contentious issue as the Royal Mail owns the rights to the UK's postcode database but Coast is also involved in a project called Free The Postcode which would provide the information for free.
He said: "We don't have to get every single one of the 1.9 million postcodes in the UK but if we can get to [a density of] 50 or 100 metres or something like that it becomes useful to a lot of people."
The Ordnance Survey, which derives much of its revenue from selling mapping data to commercial partners, said there is room for both models in the market and is also trialling a scheme to open up some its secret code to allow software developers to create mapping mash-ups.
Ed Parsons, chief technical officer at the Ordnance Survey, said: "There will always be a market for closed-source data. I think the two will co-exist. I could easily see OS making use of open source data or providing open source data. We are not closing our eyes. There will be the person who wants to create maps for the parish council but the utilities, for example, won't use open source data."
