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GeoJSON

GeoJSON is a geospatial data format designed for use on the web. Like other formats based on JSON (JavaScript Object Notation), it is a lightweight data-interchange format that is easy for a computer to parse, but is also relatively human-readable.

GeoJSON provides a standard way to store geospatial location information. It was originally released in 2008 as a community-developed specification, and was quickly adopted by many geospatial projects. It was later revised to become an official IETF specification (RFC 7946) in 2016. One of the major changes was that, whereas the 2008 allowed arbitrary coordinate systems, the 2016 standard mandates WGS84 (lon, lat) coordinates.

Example of a point in GeoJSON:

{
  "type": "Feature",
  "properties": {
    "name": "Walter C. Koerner Library",
    "address": "1958 Main Mall, Vancouver, BC V6T 1Z2, Canada"
  },
  "geometry": {
    "type": "Point",
    "coordinates": [
      -123.25509914782164,
      49.26669325071529
    ]
  }
}

Example of a polygon in GeoJSON:

{
  "type": "Feature",
  "properties": {
    "name": "Walter C. Koerner Library",
    "address": "1958 Main Mall, Vancouver, BC V6T 1Z2, Canada" 
  },
  "geometry": {
    "type": "Polygon",
    "coordinates": [
      [
        [-123.255467, 49.266867],
        [-123.2550320, 49.266320],
        [-123.254822, 49.266392],
        [-123.255256, 49.266948],
        [-123.255467, 49.266867]
      ]
    ]
  }
}

Things to know about GeoJSON:

  • Coordinates
    • All coordinates are in WGS84 (EPSG:4326) in longitude, latitude order
    • 7 digits past the decimal point (0.0000001) is about 1cm precision
  • Geometries
    • Geometries can be points, lines, or polygons (or any combination even in the same file)
    • Geometries may also be multipoints, multilines, or multipolygons (think Hawaii)
    • Polygons may have holes, holes with islands, holes with islands with holes, etc.
  • Properties
    • Property names can be very long (whereas shapefiles are limited to 10 characters)
    • Property names can contain spaces and non-alphanumeric characters (although perhaps not recommended)
    • The order of properties is not significant
    • Property values are either text strings or numbers (real or integer)
    • Double quotes in strings must be escaped as \"
    • Single quotes can also be escaped, but it is not required
  • Online tools
  • GeoJSON is not recommended for very large datasets

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