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Geospatial Query Operators

$geoIntersects

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  • Definition
  • Behavior
  • Examples

Definition

$geoIntersects

Selects documents whose geospatial data intersects with a specified GeoJSON object; i.e. where the intersection of the data and the specified object is non-empty.

The $geoIntersects operator uses the $geometry operator to specify the GeoJSON object. To specify a GeoJSON polygons or multipolygons using the default coordinate reference system (CRS), use the following syntax:

{
  <location field>: {
     $geoIntersects: {
        $geometry: {
           type: "<GeoJSON object type>" ,
           coordinates: [ <coordinates> ]
        }
     }
  }
}

For $geoIntersects queries that specify GeoJSON geometries with areas greater than a single hemisphere, the use of the default CRS results in queries for the complementary geometries.

To specify a single-ringed GeoJSON polygon with a custom MongoDB CRS, use the following prototype that specifies the custom MongoDB CRS in the $geometry expression:

{
  <location field>: {
     $geoIntersects: {
        $geometry: {
           type: "Polygon" ,
           coordinates: [ <coordinates> ],
           crs: {
              type: "name",
              properties: { name: "urn:x-mongodb:crs:strictwinding:EPSG:4326" }
           }
        }
     }
  }
}

The custom MongoDB CRS uses a counter-clockwise winding order and allows $geoIntersects to support queries with a single-ringed GeoJSON polygon whose area is greater than or equal to a single hemisphere. If the specified polygon is smaller than a single hemisphere, the behavior of $geoIntersects with the MongoDB CRS is the same as with the default CRS. See also "Big" Polygons.

Important

If specifying latitude and longitude coordinates, list the longitude first, and then latitude.

  • Valid longitude values are between -180 and 180, both inclusive.

  • Valid latitude values are between -90 and 90, both inclusive.

Behavior

Geospatial Indexes

$geoIntersects uses spherical geometry. $geoIntersects does not require a geospatial index. However, a geospatial index will improve query performance. Only the 2dsphere geospatial index supports $geoIntersects.

Degenerate Geometry

$geoIntersects does not guarantee that it will consider a polygon to intersect with its own edges; its own vertices; or another polygon sharing vertices or edges but no interior space.

"Big" Polygons

For $geoIntersects, if you specify a single-ringed polygon that has an area greater than a single hemisphere, include the custom MongoDB coordinate reference system in the $geometry expression. Otherwise, $geoIntersects queries for the complementary geometry. For all other GeoJSON polygons with areas greater than a hemisphere, $geoIntersects queries for the complementary geometry.

Examples

Intersects a Polygon

The following example uses $geoIntersects to select all loc data that intersect with the Polygon defined by the coordinates array. The area of the polygon is less than the area of a single hemisphere:

db.places.find(
   {
     loc: {
       $geoIntersects: {
          $geometry: {
             type: "Polygon" ,
             coordinates: [
               [ [ 0, 0 ], [ 3, 6 ], [ 6, 1 ], [ 0, 0 ] ]
             ]
          }
       }
     }
   }
)

For single-ringed polygons with areas greater than a single hemisphere, see Intersects a "Big" Polygon.

Intersects a "Big" Polygon

To query with a single-ringed GeoJSON polygon whose area is greater than a single hemisphere, the $geometry expression must specify the custom MongoDB coordinate reference system. For example:

db.places.find(
   {
     loc: {
       $geoIntersects: {
          $geometry: {
             type : "Polygon",
             coordinates: [
               [
                 [ -100, 60 ], [ -100, 0 ], [ -100, -60 ], [ 100, -60 ], [ 100, 60 ], [ -100, 60 ]
               ]
             ],
             crs: {
                type: "name",
                properties: { name: "urn:x-mongodb:crs:strictwinding:EPSG:4326" }
             }
          }
       }
     }
   }
)

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Geospatial Query Operators