$geoIntersects

Definition

• $geoIntersects
• Selects documents whose geospatial data intersects with a specifiedGeoJSON object; i.e. wherethe intersection of the data and the specified object is non-empty.

The $geoIntersects operator uses the $geometryoperator to specify the GeoJSON object. To specify a GeoJSONpolygons or multipolygons using the default coordinate referencesystem (CRS), use the following syntax:

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

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

New in version 3.0: To specify a single-ringed GeoJSON polygon with a custom MongoDB CRS, use the followingprototype 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 andallows $geoIntersects to support queries with asingle-ringed GeoJSON polygon whose area isgreater than or equal to a single hemisphere. If the specifiedpolygon is smaller than a single hemisphere, the behavior of$geoIntersects with the MongoDB CRS is the same as with thedefault CRS. See also “Big” Polygons.

Important

If specifying latitude and longitude coordinates, list thelongitude first and then latitude:

• Valid longitude values are between -180 and 180, bothinclusive.
• Valid latitude values are between -90 and 90, bothinclusive.

Behavior

Geospatial Indexes

$geoIntersects uses spherical geometry.$geoIntersects does not require a geospatial index. However, ageospatial index will improve query performance. Only the2dsphere geospatial index supports$geoIntersects.

Degenerate Geometry

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

“Big” Polygons

For $geoIntersects, if you specify a single-ringed polygon thathas an area greater than a single hemisphere, include thecustom MongoDB coordinate reference system in the $geometry expression; otherwise, $geoIntersects queries forthe complementary geometry. For all other GeoJSON polygons with areasgreater than a hemisphere, $geoIntersects queries for thecomplementary geometry.

Examples

Intersects a Polygon

The following example uses $geoIntersects to select allloc data that intersect with the Polygon defined bythe coordinates array. The area of the polygon is less than thearea 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 greaterthan a single hemisphere, the $geometry expression mustspecify 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" }
             }
          }
       }
     }
   }
)