GeoJSON

From Wikipedia, the free encyclopedia
GeoJSON
Filename extension .json
Internet media type application/json
Type of format GIS file format
Extended from JSON
Open format? yes
Website geojson.org

GeoJSON[1] is an open standard format for encoding collections of simple geographical features along with their non-spatial attributes using JavaScript Object Notation. The features include points (therefore addresses and locations), line strings (therefore streets, highways and boundaries), polygons (countries, provinces, tracts of land), and multi-part collections of these types. GeoJSON features need not represent entities of the physical world only; mobile routing and navigation apps, for example, might describe their service coverage using GeoJSON.[2]

The GeoJSON format differs from other GIS standards in that it was written and is maintained not by a formal standards organization, but by an Internet working group of developers.[3]

A notable offspring of GeoJSON is the TopoJSON format.

History

The GeoJSON format working group and discussion were begun in March 2007[4] and the format specification was finalized in June 2008.

Example

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [102.0, 0.5]
      },
      "properties": {
        "prop0": "value0"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "LineString",
        "coordinates": [
          [102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]
        ]
      },
      "properties": {
        "prop1": 0.0,
        "prop0": "value0"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0],
            [100.0, 0.0]
          ]
        ]
      },
      "properties": {
        "prop1": {
          "this": "that"
        },
        "prop0": "value0"
      }
    }
  ]
}

Geometries

Geometry primitives
Type Examples
Point 
{
    "type": "Point", 
    "coordinates": [30, 10]
}
LineString 
{
    "type": "LineString", 
    "coordinates": [
        [30, 10], [10, 30], [40, 40]
    ]
}
Polygon 
{
    "type": "Polygon", 
    "coordinates": [
        [[30, 10], [40, 40], [20, 40], [10, 20], [30, 10]]
    ]
}

{
    "type": "Polygon", 
    "coordinates": [
        [[35, 10], [45, 45], [15, 40], [10, 20], [35, 10]], 
        [[20, 30], [35, 35], [30, 20], [20, 30]]
    ]
}
Multipart geometries
Type Examples
MultiPoint 
{
    "type": "MultiPoint", 
    "coordinates": [
        [10, 40], [40, 30], [20, 20], [30, 10]
    ]
}
MultiLineString 
{
    "type": "MultiLineString", 
    "coordinates": [
        [[10, 10], [20, 20], [10, 40]], 
        [[40, 40], [30, 30], [40, 20], [30, 10]]
    ]
}
MultiPolygon 
{
    "type": "MultiPolygon", 
    "coordinates": [
        [
            [[30, 20], [45, 40], [10, 40], [30, 20]]
        ], 
        [
            [[15, 5], [40, 10], [10, 20], [5, 10], [15, 5]]
        ]
    ]
}

{
    "type": "MultiPolygon", 
    "coordinates": [
        [
            [[40, 40], [20, 45], [45, 30], [40, 40]]
        ], 
        [
            [[20, 35], [10, 30], [10, 10], [30, 5], [45, 20], [20, 35]], 
            [[30, 20], [20, 15], [20, 25], [30, 20]]
        ]
    ]
}

Supported software

GeoJSON is supported by numerous mapping and GIS software packages, including OpenLayers,[5] Leaflet, Geoforge software,[6] GeoServer,[7] GeoDjango,[8] GDAL,[9] Safe Software FME,[10] and CartoDB,[11] It is also possible to use GeoJSON with PostGIS[12] and Mapnik,[13] both of which handle the format via the GDAL OGR conversion library. Bing Maps, Yahoo! and Google also support GeoJSON in their API services.

Google Maps integration is possible using libraries,[14] or by iterating through the data and instancing equivalent objects.

GitHub also supports GeoJSON rendering.[15]

References

  1. ↑ The GeoJSON Format Specification
  2. ↑ iOS Location and Maps Programming Guide
  3. ↑ The GeoJSON Discussion List
  4. ↑ March 2007 Archives by thread
  5. ↑ http://openlayers.org/dev/examples/vector-formats.html
  6. ↑ http://leafletjs.com/reference.html#geojson
  7. ↑ http://svn.codehaus.org/geoserver/tags/2.0.0-alpha1/geoserver/release/README.txt
  8. ↑ http://geodjango.org/docs/db-api.html
  9. ↑ http://gdal.org/ogr/drv_geojson.html
  10. ↑ http://www.safe.com/reader_writerPDF/geojson.pdf
  11. ↑ http://developers.cartodb.com/documentation/cartodb-js.html
  12. ↑ http://pugs.postgresql.org/files/Introduction_to_PostGIS_v1.0.pdf
  13. ↑ http://svn.mapnik.org/tags/release-0.6.0/docs/api_docs/python/mapnik-module.html
  14. ↑ https://github.com/JasonSanford/GeoJSON-to-Google-Maps
  15. ↑ https://github.com/blog/1528-there-s-a-map-for-that

Sources

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