OpenStreetMap: Grassroots Mapping

OpenStreetMap was founded with the goal of creating and providing free geographic data to whoever wants it. With an army of 5,000 volunteers who hit the streets around the world with GPS units to capture street segments or who participate in applying attribute information to collected data, the project has growing geographic data in thirty-nine countries to date. The project, started by Steve Coast in 2004, grew out of his desire to create a local map of his own neighborhood. Unlike the United States which frees most federal data under that country’s Public Information Act, many countries do not freely offer data created through public funds back to the public.

The collaboration website OpenStreetMap is functioning in a wiki environment which allows collaborators the ability to post progress in geographic data collection for the various projects around the world. On the community portal page, all the OpenStreetMap projects by country is listed. The website provides different levels of resources from newbies to developers to help interested volunteers that want to get involved. There’s even a GPS Review section to help participants select a GPS unit. Many organizers create OpenStreetMap events that group volunteers together to spend a weekend collecting street data in a particular area (e.g. Isle of Wright Workshop or the OpenStreetMap Weekend in Canada).

As with all volunteered geographic information projects, the issue of spatial and attribute accuracy is of concern. The nature of the project, with volunteers collecting spatial data from a variety of GPS units and onscreen digitizing will undoubtedly lead to severe errors on parts of the map. In OpenStreetMap’s FAQ section, the web site responds to this by saying, “OpenStreetMap is a free editable map of the whole world. It is made by people like you. Which means the database will always be subject to the whims, experimentation, and mistakes of the community; this is precisely OSM’s strength since, among other things, it allows our data to quickly accommodate changes in the physical world.” An independent study using ground truthing would be needed to assess the relative accuracy of such a project and to see if this type of community based mapping model can truly yield a complete and accurate spatial dataset of this magnitude.

OpenStreetMap Project and related sites:

• OpenStreetMap Web Site
• OpenGeoData Blog
• Interview with Steve Coast, Founder of OpenStreetMap