New Times,
New Thinking.

25 May 2007

Mapping for the people

By Gregory Marler

In an earlier blog posting I explained GPS and how you can use it for recreational activities. Now think if the GPS reciever recorded your position every second and you walked along a road, you’d get a file that can be represented as a dotted line. Walk down some more roads recording as you go and you’ll soon have something resembling a street map. A nomination in the Information and openness category, Open Street Map, has been using the technology in this way to create maps that are free from the restrictions that come with the maps we currently use.

One of the best ways to be part of Open Street Map(OSM) is to go along to one of the Mapping Weekends that are organised throughout the year, as I did a few weeks ago. On a Saturday morning a small group of people met in a Southampton classroom for introductions and to divide up the areas of the city that aren’t fully mapped – at least by this project. With GPS receivers in hand we all set out, most on foot but I joined the founder, Steve Coast, in his car for a vital co-pilot role. The plan is simply to go down every road we spot while the GPS records the line of the roads. At every turning I would press a button on the GPSr to save a waypoint (a location bookmark) and write down the name of the road we turned into. It’s not only roads that are useful to have on a map, so I also saved waypoints every time we passed a pub, postbox, church, or school and noted it’s name along with the side of the road it was on.

When I was back home I uploaded the GPS data onto my computer and opened the file (the standard SatNav systems don’t tend to have this recording function) in one of the editors that have been specifically developed for OSM. In this case I used JOSM. It seems like a lot of random dots at first, but as some of them are marked with the waypoint numbers I can refer to my notes to see what’s there. After tracing the dots and marking them with tags such as name = The Avenue, road type, place of worship, or amenity=pub, then I can send the information to update the OSM database. By uploading the data to the database mappers agree to license it under a creative commons agreement, similar to open source software philosophy, this allows anyone to use the map data for whatever they like as long as it’s credited and anything coming from it continues to be shared.
The Open Street Map also works like a wiki, not an encyclopedia made up of words but a wiki-map where if someone knows that a road has been demolished recently, or they know the name of a road that didn’t have a road sign, they can edit the map using specially developed tools.

You may wonder why I couldn’t just trace some existing map rather than go out and get weird looks from locals as I wonder down to the end of every road as if I’m completely lost. Well first of all this method of mapping doesn’t use information that someone else owns the copyright to. Most places you see a map, e.g. MultiMap, Street Map, and those paper maps you can never fold correctly, use maps from one of the main organisations such as Ordnance Survey and because Ordnance Survey hold the copyright they can license the maps how they like, usually in a manner that involves an annual charge.

So small organisations and charities wanting to maps on their website or a leaflet will need to pay the fee, and anyone wanting to be creative or innovative with maps or map data will have to pay yearly for the work they create and will be restricted on the ability to pass it on.

The second reason for physically going out and taking the GPSr down every road right to the dead ends is for accuracy. You may not think it but the maps you use can have errors, for example a straight road going down a hill could be mapped with a kink in it because it’s been traced from aerial photography. The mapping organisations even make deliberate mistakes like adding a fictional road in so that they can tell if anyone copied them – for example the mythical Lye Close. Because OSM freely shares its maps it doesn’t need to worry about illegal copiers and because it’s a form of wiki anyone can contribute changes so it stays up to date.

In the last two years the coverage and detail of the world mapped for OSM has rapidly grown making most major roads in the UK complete and mapping parties/weekends now focus on detail and outlying town areas. In November a ‘slippy map’ was created to display the map, similar to that of Google maps and the new Multimap.

Open Street Map has a number of possible uses, and its openness allows this. Free Map aims to display maps suitable to walkers and although it now shares the same data as OSM, features are shown differently where they are of more interest to a walker than a standard road map user. You can try out the map and use it as and where you want, Mark Thomas’ blog has even used OSM to outline an area of restricted protest in London, once you’ve tried it out for yourself why not add your comments and rating about OSM for the New Media Awards nomination.

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