From Wikipedia, the free encyclopedia
The maps are created using data from portable GPS devices, aerial photography, other free sources or simply from local knowledge. Both rendered images and the vector graphics are available for download under a Creative Commons Attribution-ShareAlike 2.0 licence.
OpenStreetMap was inspired by sites such as Wikipedia; the map display features a prominent 'Edit' tab and a full revision history is maintained. Registered users can upload GPS track logs and edit the vector data using the given editing tools.
OpenStreetMap (OSM) was founded in July 2004 by Steve Coast. In April 2006, a 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 August 2007 an independent project, OpenAerialMap, was launched, to hold a database of aerial photography available on open licensing and 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.
In January 2008, functionality was made available to download map data into a GPS unit for use by cyclists. 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 will use OpenStreetMap data.
The initial map data was built from scratch by volunteers performing systematic ground surveys using a handheld GPS unit and a notebook, digital camera, or a voice recorder. This data was 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.When large datasets are available a technical team will manage the conversion and import of the data.
Ground surveys are performed by a mapper, on foot, bicycle or in a car or boat. Map data are usually collected using a GPS unit, although this isn't 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 it on the project's website. At that point in time, 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. This is usually done by the same mapper, sometimes by other users 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 are systematically mapping whole towns and cities over a period of time, or organising mapping parties to intensively map a particular area over an evening or a weekend. In addition to structured surveys, a large number of smaller edits are made by contributors to correct errors or add features.