OpenStreetMap

OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world. Two major driving forces behind the establishment and growth of OSM have been restrictions on use or availability of map information across much of the world and the advent of inexpensive portable satellite navigation devices.

Created by Steve Coast in the UK in 2004, it was inspired by the success of Wikipedia and preponderance of proprietary map data in the UK and elsewhere. Since then, it has grown to over 1 million registered users, who can collect data using GPS devices, aerial photography, and other free sources. These crowdsourced data are then made available under the Open Database License. The site is supported by the OpenStreetMap Foundation, a non-profit organization registered in England.

Rather than the map itself, the data generated by the OpenStreetMap project are considered its primary output. These data are then available for use in both traditional applications, like their usage by Craigslist, Geocaching, MapQuest Open, JMP statistical software, and Foursquare to replace Google Maps, and more unusual roles, like replacing default data included with GPS receivers. These data have been favourably compared with proprietary datasources, though data quality varies worldwide.

History


Steve Coast founded the project in 2004, initially focusing on mapping the United Kingdom. In the UK and elsewhere, government-run and tax-funded projects like the Ordnance Survey created massive datasets but failed to freely and widely distribute them. In April 2006, the OpenStreetMap Foundation was established to encourage the growth, development and distribution of free geospatial data and provide geospatial data for anybody to use and share. In December 2006, Yahoo confirmed that OpenStreetMap could use its aerial photography as a backdrop for map production.

In April 2007, Automotive Navigation Data (AND) donated a complete road data set for the Netherlands and trunk road data for India and China to the project and by July 2007, when the first OSM international The State of the Map conference was held, there were 9,000 registered users. Sponsors of the event included Google, Yahoo and Multimap. In October 2007, OpenStreetMap completed the import of a US Census TIGER road dataset. In December 2007, Oxford University became the first major organisation to use OpenStreetMap data on their main website.

Ways to import and export data have continued to grow – by 2008, the project developed tools to export OpenStreetMap data to power portable GPS units, replacing their existing proprietary and out-of-date maps. In February 2008, a series of workshops were held in India. In March, two founders announced that they have received venture capital funding of 2.4M euros for CloudMade, a commercial company that uses OpenStreetMap data.

In 2012, the launch of pricing for Google Maps led several prominent websites to switch from their service to OpenStreetMap and other competitors. Chief amongst these were Foursquare, Craigslist who adopted OpenStreetMap, and Apple, Inc, which ended a contract with Google and launched a self-built mapping platform which uses TomTom and OpenStreetMap data.

Contributors


The project has a geographically diverse user-base, due to emphasis of local knowledge and ground truth in the process of data collection. Many early contributors are cyclists who survey with and for bicycles, charting cycleroutes and navigable trails. Others are GIS professionals who contribute data with Esri tools.

By August 2008, shortly after the second The State of the Map conference was held, there were over 50,000 registered contributors; by March 2009, there were 100,000 and by the end of 2009 the figure was nearly 200,000. In April 2012, OpenStreetMap cleared 600,000 registered contributors. On January 6, 2013, OpenStreetMap reached 1 million registered users, a minority of whom contribute the majority of content. Around 30% of users have contributed at least one point to the OpenStreetMap database.

State Of The Map
Since 2007, the OSM community has held an annual, international conference, State Of The Map. Venues have been:



Map production
The initial map data were originally collected from scratch by volunteers performing systematic ground surveys using a handheld GPS unit and a notebook, digital camera, or a voice recorder. The data were then entered into the OpenStreetMap database.

More recently, the availability of aerial photography and other data sources from commercial and government sources has greatly increased the speed of this work and has allowed land-use data to be collected more accurately by the process of digitization. When especially large datasets become available, a technical team manages the conversion and import of the data.

Surveys and personal knowledge


Ground surveys are performed by a mapper, on foot, bicycle, or in a car, motorcycle or boat. Map data are usually collected using a GPS unit, although this is not strictly necessary if an area has already been traced from satellite imagery.

Once the data have been collected, they are entered into the database by uploading them on the project's website. At that point, no information about the kind of uploaded track is available – it could be e.g., a motorway, a footpath, or a river. Thus, in a second step, editing takes place using one of several purpose-built map editors (e.g., JOSM). This is usually done by the same mapper, sometimes by other contributors registered at OpenStreetMap.

As collecting and uploading data is separated from editing objects, contribution to the project is possible also without using a GPS unit. In particular, placing and editing objects such as schools, hospitals, taxi ranks, bus stops, pubs, etc. is done based on editors' local knowledge.

Some committed contributors adopt the task of mapping whole towns and cities, or organizing mapping parties to gather the support of others to complete a map area. A large number of less active users contribute corrections and small additions to the map.

Government data
Some government agencies have released official data on appropriate licenses. Much of these data have come from the United States, where works of the federal government are placed under public domain.

In the United States, OSM uses Landsat 7 satellite imagery, Prototype Global Shorelines Prototype Global Shoreline from NOAA, and TIGER from the Census. In the UK, some Ordnance Survey OpenData are imported, while Canada's NRCan's CanVec vector data and GeoBase provides landcover and streets.

Out-of-copyright maps can be good source of information about features that do not change frequently. Copyright periods vary, but in the UK Crown copyright expires after 50 years and hence Ordnance Survey maps until the 1960s can legally be used. A complete set of UK 1 inch/mile maps from the late 1940s and early 1950s has been collected, scanned, and is available online as a resource for contributors.

Commercial data
OpenStreetMap data are assisted by companies that choose to freely license either actual street data or satellite imagery sources from which OSM contributors can trace roads and features.

Notably, Automotive Navigation Data provided a complete road data set for Netherlands and details of trunk roads in China and India. In December 2006, Yahoo! confirmed that OpenStreetMap was able to make use of their vertical aerial imagery and this photography was available within the editing software as an overlay. Contributors could create their vector based maps as a derived work, released with a free and open license, until the shutdown of the Yahoo! Maps API on 13 September 2011. In November 2010, Microsoft announced that the OpenStreetMap community could use Bing vertical aerial imagery as a backdrop in its editors. For a period from 2009 to 2011, NearMap Pty Ltd made their high-resolution PhotoMaps (currently of major Australian cities, plus some rural Australian areas) available for deriving OpenStreetMap data under a CC-BY-SA licence.

Licensing


OpenStreetMap data were originally published under a Creative Commons open content license with the intention of promoting free use and redistribution of the data. In September 2012, the license was changed to the Open Database License (ODbL) from Open Data Commons (ODC) in order to more specifically define its bearing on data rather than representation.

As part of this relicensing process, some of the map data were removed from the public distribution. This included all data contributed by members that did not agree to the new licensing terms, as well as all subsequent edits to those affected objects. It also included any data contributed based on input data that were not compatible with the new terms. Estimates suggested that over 97% of data would be retained globally, however certain regions would be affected more than others, such as in Australia where 24 to 84% of objects would be retained (depending on the type of object). Ultimately, more than 99% of the data were retained, with Australia and Poland being the countries most severely affected by the change.

All data added to the project need to have a license compatible with the Open Database License. This can include out-of-copyright information, public domain or other licenses. Contributors agree to a set of terms which require compatibility with the current license. This may involve examining licenses for government data to establish whether they are compatible.

Software used in the production and presentation of OpenStreetMap data is available from many different projects and each may have their own licencing. The application — what users access to edit maps and view changelogs, is powered by Ruby on Rails. The application also uses PostgreSQL for storage of user data and edit metadata. The default map is rendered by Mapnik, stored in PostGIS, and powered by an Apache module called mod_tile. Certain parts of the software, such as the map editor Potlatch2, have been made available as public domain.

Operation
While OpenStreetMap aims to be a central data source, its map rendering and aesthetics are meant to be only one of many options, some which highlight different elements of the map or emphasize design and performance. The OpenStreetMap project keeps a list of OSM-based services which serves as a complete reference.

Commercial services


A variety of popular services incorporate some sort of geolocation or map-based component. Notable services using OSM for this include:

Apple Inc unexpectedly created an OpenStreetMap-based map for iPhoto for iOS on March 7, 2012, and launched the maps without properly citing the data source – though this was corrected in 1.0.1. OpenStreetMap is one of the many cited sources for Apple's custom maps in iOS 6, though the majority of map data is provided by TomTom.

Flickr uses OpenStreetMap data for various cities around the world, including Baghdad, Beijing, Kabul, Santiago, Sydney, and Tokyo. In 2012, the maps switched to use Nokia data primarily, with OSM being used in areas where the commercial provider lacked performance. MapQuest announced a service based on OpenStreetMap in 2010, which eventually became MapQuest Open.

On 29 February 2012, Foursquare started using OpenStreetMap via MapBox's rendering and infrastructure. Craigslist also switched to OpenStreetMap in 2012, rendering their own tiles based on the data.

In 2009, Hasbro, the games company behind the property trading board game Monopoly, launched Monopoly City Streets, a massively multiplayer online game which allowed players to "buy" streets all over the world. The game used map tiles from Google Maps and the Google Maps API to display the game board, but the underlying street data were obtained from OpenStreetMap. The online game was meant to be a limited time offering, closing at the end of January 2010.

Moovit uses maps based on OpenStreetMap in their free mobile application for public transit navigation.

Pictometry uses OpenStreetMap as the default map in their web based products for displaying their patented 3D aerial photography.

Wikipedia uses OpenStreetMap data to render custom maps used by the articles. Many languages are included in the WIWOSM project (Wikipedia Where in OSM) which aims to show OSM objects on a slippy map, directly visible on the article page.

Dublin-based indie games developer Ballardia launched World of the Living Dead: Resurrection in October 2013, which has incorporated OpenStreetMaps into its game engine, along with census information to create a browser-based game mapping over 14,000 square kilometres of greater Los Angeles and survival strategy gameplay. Its previous incarnation had used Google Maps, which had proven incapable of supporting high volumes of players, so during 2013 they shut down the Google Maps version and ported the game to OSM.

Humanitarian aid
During the 2010 Haiti earthquake, OpenStreetMap and Crisis Commons volunteers used available satellite imagery to map the roads, buildings and refugee camps of Port-au-Prince in just two days, building "the most complete digital map of Haiti's roads".

The resulting data and maps have been used by several organisations providing relief aid, such as the World Bank, the European Commission Joint Research Centre, the Office for the Coordination of Humanitarian Affairs, UNOSAT and others.

NGOs like the Humanitarian OpenStreetMap Team and others have worked with donors like USAID to map other parts of Haiti and parts of many other countries, both to create map data for places that formerly were blank, and to engage and build capacity of local people.

Along with post-disaster work, the Humanitarian OpenStreetMap Team has worked to build better risk models for Uganda and elsewhere, in partnership with the Red Cross, World Bank, and other humanitarian groups.

Software for viewing maps


The web site OpenStreetMap.org provides a slippy map interface based on the Leaflet javascript library (and formerly built on OpenLayers), displaying map tiles rendered by the Mapnik rendering engine, and tiles from other sources including OpenCycleMap.org and MapQuest Open. Maps can also be generated offline by a local installation of Mapnik and downloaded map data.

OpenStreetMap maintains lists of online and offline routing engines available, such as the Open Source Routing Machine. The OSM data is popular with routing researchers, and is also available to open-source projects and companies to build routing applications (or for any other purpose).

Software for editing maps
Editing of maps can be done using the default web browser editor called iD, an HTML5 application using d3.js and written by MapBox. The earlier Flash-based application Potlatch is retained for intermediate-level users. JOSM and Merkaartor are more powerful desktop editing applications that are better suited for advanced users.

Data format
OpenStreetMap uses a topological data structure, with four core elements (also known as data primitives):
 * Nodes are points with a geographic position, stored as coordinates (pairs of a latitude and a longitude) according to WGS 84. Outside of their usage in ways, they are used to represent map features without a size, such as points of interest or mountain peaks.
 * Ways are ordered lists of nodes, representing a polyline, or possibly a polygon if they form a closed loop. They are used both for representing linear features such as streets and rivers, and areas, like forests, parks, parking areas and lakes.
 * Relations are ordered lists of nodes, ways and relations (together called "members"), where each member can optionally have a "role" (a string). Relations are used for representing the relationship of existing nodes and ways. Examples include turn restrictions on roads, routes that span several existing ways (for instance, a long-distance motorway), and areas with holes.
 * Tags are key-value pairs (both arbitrary strings). They are used to store metadata about the map objects (such as their type, their name and their physical properties). Tags are not free-standing, but are always attached to an object: to a node, a way, a relation, or to a member of a relation. A recommended ontology of map features (the meaning of tags) is maintained on a wiki.

The LinkedGeoData data set is a work of the Agile Knowledge Engineering and Semantic Web (AKSW) research group at the University of Leipzig, a group mostly known for DBpedia, that uses the GeoSPARQL and well-known text (WKT) RDF vocabularies to represent OpenStreetMap data.