Global Polygon – Representing the Whole Earth as a Polygon in GeoJSON

areageojsonspherical-geometry

This is related to determining the interior of a Polygon.

My difficulty is that if I specify a Polygon covering the Earth going from East to West, it will still have a boundary along the antemeridian, which would show up in azimuthal projections. For example, in GeoJSON:

{
  "type": "Polygon",
  "coordinates": [
    [[-180, -90], [-180, 90], [180, 90], [180, -90], [-180, -90]]
  ]
}

Is there a standard way to specify a whole-sphere Polygon, with no boundary?

I've thought about using an empty exterior ring:

{
  "type": "Polygon",
  "coordinates": [
    []
  ]
}

The logic being that I could specify further rings as holes to be punched into the whole-sphere Polygon.

Unfortunately, GeoJSON stipulates that LinearRings must have at least 4 points, so this would be straying from the specification. However, I'm still interested in understanding whether this approach is taken anywhere else.

Best Answer

Since there doesn't seem to be a standard way to represent this somewhat rare situation of a polygon with no boundary covering the whole Earth, we decided to add our own {type: "Sphere"}, which has worked remarkably well for our purposes.

We decided not to use a Polygon containing an empty LinearRing, since this more intuitively represents an empty polygon and could easily lead to confusion and accidental creation of whole-Earth polygons.

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