geo_intersects_2polygons()

  • Article

Applies to: ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel

Calculates whether two polygons or multipolygons intersect.

Syntax

geo_intersects_2polygons(polygon1,polygon1)

Learn more about syntax conventions.

Parameters

Name Type Required Description
polygon1 dynamic ✔️ Polygon or multipolygon in the GeoJSON format.
polygon2 dynamic ✔️ Polygon or multipolygon in the GeoJSON format.

Returns

Indicates whether two polygons or multipolygons intersect. If the Polygon or the MultiPolygon are invalid, the query will produce a null result.

Note

  • The geospatial coordinates are interpreted as represented by the WGS-84 coordinate reference system.
  • The geodetic datum used for measurements on Earth is a sphere. Polygon edges are geodesics on the sphere.
  • If input polygon edges are straight cartesian lines, consider using geo_polygon_densify() to convert planar edges to geodesics.

Polygon definition and constraints

dynamic({"type": "Polygon","coordinates": [LinearRingShell, LinearRingHole_1, ..., LinearRingHole_N]})

dynamic({"type": "MultiPolygon","coordinates": [[LinearRingShell, LinearRingHole_1, ..., LinearRingHole_N], ..., [LinearRingShell, LinearRingHole_1, ..., LinearRingHole_M]]})

  • LinearRingShell is required and defined as a counterclockwise ordered array of coordinates [[lng_1,lat_1], ..., [lng_i,lat_i], ...,[lng_j,lat_j], ...,[lng_1,lat_1]]. There can be only one shell.
  • LinearRingHole is optional and defined as a clockwise ordered array of coordinates [[lng_1,lat_1], ...,[lng_i,lat_i], ...,[lng_j,lat_j], ...,[lng_1,lat_1]]. There can be any number of interior rings and holes.
  • LinearRing vertices must be distinct with at least three coordinates. The first coordinate must be equal to the last. At least four entries are required.
  • Coordinates [longitude, latitude] must be valid. Longitude must be a real number in the range [-180, +180] and latitude must be a real number in the range [-90, +90].
  • LinearRingShell encloses at most half of the sphere. LinearRing divides the sphere into two regions. The smaller of the two regions will be chosen.
  • LinearRing edge length must be less than 180 degrees. The shortest edge between the two vertices will be chosen.
  • LinearRings must not cross and must not share edges. LinearRings may share vertices.
  • Polygon contains its vertices.

Tip

Use literal LineString or MultiLineString for better performance.

Examples

The following example checks whether some two literal polygons intersects.

let polygon1 = dynamic({"type":"Polygon","coordinates":[[[-73.9630937576294,40.77498840732385],[-73.963565826416,40.774383111780914],[-73.96205306053162,40.773745311181585],[-73.96160781383514,40.7743912365898],[-73.9630937576294,40.77498840732385]]]});
let polygon2 = dynamic({"type":"Polygon","coordinates":[[[-73.96213352680206,40.775045280447145],[-73.9631313085556,40.774578106920345],[-73.96207988262177,40.77416780398293],[-73.96213352680206,40.775045280447145]]]});
print geo_intersects_2polygons(polygon1, polygon2)

Output

print_0
True

The following example finds all counties in the USA that intersect with area of interest literal polygon.

let area_of_interest = dynamic({"type":"Polygon","coordinates":[[[-73.96213352680206,40.775045280447145],[-73.9631313085556,40.774578106920345],[-73.96207988262177,40.77416780398293],[-73.96213352680206,40.775045280447145]]]});
US_Counties
| project name = features.properties.NAME, county = features.geometry
| where geo_intersects_2polygons(county, area_of_interest)
| project name

Output

name
New York

The following example will return a null result because one of the polygons is invalid.

let central_park_polygon = dynamic({"type":"Polygon","coordinates":[[[-73.9495,40.7969],[-73.95807266235352,40.80068603561921],[-73.98201942443848,40.76825672305777],[-73.97317886352539,40.76455136505513],[-73.9495,40.7969]]]});
let invalid_polygon = dynamic({"type":"Polygon"});
print isnull(geo_intersects_2polygons(invalid_polygon, central_park_polygon))

Output

print_0
True