OpenStreetMap: Grassroots Mapping

Caitlin Dempsey


OpenStreetMap was founded with the goal of creating and providing free geographic data to whoever wants it. With more than 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.

Who started OpenStreetMap?

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.

Pocket-lint has an interview with Steve Coast, the founder and developer of OpenStreetMap which uses crowdsourcing to create and update detailed geographic information. 

The article focuses mainly on comparing the costs and update capability of commercial sources such as TeleAtlas with the advances of OpenStreetMap which relies on the input of over 150,000 volunteers. 

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As for the long term goals of OpenStreetMap, Steve Coast says, “The plan is to overtake Tele Atlas and Navteq. It’s coming for them and it’ll hit them hard like it did for the guys at Encyclopedia Britannica when Wikipedia grew. I want OSM to become the biggest mapping service in the world.

How does OpenStreetMap work to collect GIS data?

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).

Ensuring spatial accuracy

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’s Growth

BeyoNav, which analyzes the growth of OpenStreetMap data (OSM), has released metrics in March of 2012 looking at the growth of street data within the crowdsourced GIS data gathering project.  

OpenStreetMap data was analyzed using BEYONAV’s proprietary BeyoViewer software package.  Looking at the entire planet OSM dataset, BeyoNav found that there was a growth of 75% in 2011, and over 150% over the last two years.  

On average during 2011, each week saw over 96,000 kilometers of new roadway added to OSM as compared to an average of 64,000 kilometers of roadway added weekly in 2010.

OpenStreetMap is gaining momentum and growing acceptance as a mapping service, with several notable companies switching out mapping services from Google Maps to OSM.  MapQuest offers a free mapping service built on OpenStreetMap data called Open MapQuest.

BeyoNav has produced a graph showing the rate of growth of the various components of OpenStreetMap roadway data.  The weekly data used in the graph can be viewed here.

OpenStreetMap Data Growth since 2010.  Source: BeyoNav.
OpenStreetMap Data Growth since 2010. Source: BeyoNav.

This is the second year that BeyoNav has analyzed the growth of OpenStreetMap data.  In 2010 an analysis was performed and a report produced entitled “Geo-Analytics on OpenStreetMap Road Data“.

BeyoNav is predicting that 2012 will be a banner year for OpenStreetMap, citing the following arguments:

  • MapQuest’s free Open JavaScript Maps API puts brawn and heft behind serving OSM data online easily to any website or JavaScript developer, which the OpenStreetMap Foundation is does not provide.
  • The Google Maps API has up until now been completely free for any Internet facing, publicly accessible web site. Google has stated that they will begin charging web sites that exceed certain usage thresholds imminently.
  • A sophisticated desktop editor JOSM was released for editing OSM data, putting power into the hands of contributors.
  • Support by GIS Analysis packages like QuantumGIS put OSM data into the hands of contributors and analysts who wish to use OSM data on the desktop.
  • As BEYONAV’s analysis shows, the OSM database has matured far beyond being simply an inferior free and open source alternative to commercial data sources. The rapid and steady pace of growth assures potential commercial users that this is a sustainable and solid foundation upon which to entrust their business plans.
  • The OSM Google+ stream includes countless mentions of companies recently switching from Google Maps to OSM

Growing Adoption of OpenStreetMap Services

OpenStreetMap gained two new big services in March of 2012 with the disclosure by FourSquare and Apple that have picked up the crowdsourcing map favorite.  

This news also marked the departure from Google Maps for these two companies as their mapping source.  Foursquare made its announcement on February 29th, stating:

Starting today, we’re embracing the OpenStreetMap movement, so all the maps you see when you go to will look a tiny bit different (we think the new ones are really pretty).

Citing the recent movement of other services from Google to OpenStreetMap as part of the impetus to change, foursquare has chosen MapBox Streets to power the millions of map image tiles that foursquare uses.

Apple’s dropping of Google Maps within its iPhoto app was done without any announcement but led to a flurry of interest among bloggers and those watching Apple’s every move.  What was puzzling to many was the use of outdated OpenStreetMap data and the lack of attribution of the source data.  OpenStreetMap ended up making the welcome announcement of Apple’s mapping service change, noting:

The OSM data that Apple is using is rather old (start of April 2010) so don’t expect to see your latest and greatest updates on there. It’s also missing the necessary credit to OpenStreetMap’s contributors; we look forward to working with Apple to get that on there.

The post from OpenStreetMap notes that Ivan Sanchez has a nice web application that allows viewers the ability to compare Apple’s iPhoto maps with current OpenStreetMap data.

OpenStreetMap on MapBox Streets.
OpenStreetMap on MapBox Streets.

OpenStreetMap Project and related sites:

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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.