OpenStreetMap: ការផលិត-បង្កើតផែនទី

ការផលិត-បង្កើតផែនទី
thumb|Recording a GPS trace.

Technique
The initial map data were collected from scratch by volunteers performing systematic ground surveys using a handheld GPS unit and a notebook, digital camera, or a voice recorder. These 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.

When large datasets are available, a technical team manages the conversion and import of the data.

Structured ground surveys
thumb|left|Raw GPS data (tracklogs) for Hedge End.
thumb|Varying accuracy of GPS tracks from different GPS receivers
thumb|Surveying during a family excursion can inspire and lead to changed routes
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 is not strictly necessary if an area has already been traced from satellite imagery.

Once the data has been collected, it is 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.

ប្រភពទិន្នន័យពីរដ្ឋាភិបាល
Some government agencies have released official data on appropriate licenses. Much of this data has come from the United States, where the federal government does not copyright such data. See Copyright status of work by the U.S. government for more details.

 Landsat 7 satellite imagery
 Prototype Global Shorelines (PGS)
 TIGER data of the United States
 Ordnance Survey OpenData
 NRCan's CanVec vector data and GeoBase's vector data sets of Canada
 The National Map (USGS)

Various authorities have also made more local detailed aerial photography available on suitable licenses through OpenAerialMap.

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.

ប្រភពទិន្នន័យពីឯកជន
Some commercial companies have donated data to the project on suitable licenses. 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 September 13, 2011.

In November 2010, Microsoft announced that the OpenStreetMap community could use Bing vertical aerial imagery as a backdrop in its editors.

NearMap Pty Ltd have, since launch in November 2009, 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.