Description

For geometry type returns the minimum 2D Cartesian distance between two geometries in projected units (spatial ref units). For geography type defaults to return the minimum geodesic distance between two geographies in meters. If use_spheroid is false, a faster sphere calculation is used instead of a spheroid.

This method implements the OpenGIS Simple Features Implementation Specification for SQL 1.1.

This method implements the SQL/MM specification. SQL-MM 3: 5.1.23

This method supports Circular Strings and Curves

This method is also provided by SFCGAL backend.

Availability: 1.5.0 geography support was introduced in 1.5. Speed improvements for planar to better handle large or many vertex geometries

Enhanced: 2.1.0 improved speed for geography. See Making Geography faster for details.

Enhanced: 2.1.0 - support for curved geometries was introduced.

Enhanced: 2.2.0 - measurement on spheroid performed with GeographicLib for improved accuracy and robustness. Requires Proj >= 4.9.0 to take advantage of the new feature.

Basic Geometry Examples

--Geometry example - units in planar degrees 4326 is WGS 84 long lat unit=degrees
SELECT ST_Distance(
		'SRID=4326;POINT(-72.1235 42.3521)'::geometry,
		'SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)'::geometry
	);
st_distance
-----------------
0.00150567726382282

-- Geometry example - units in meters (SRID: 3857, proportional to pixels on popular web maps)
-- although the value is off, nearby ones can be compared correctly,
-- which makes it a good choice for algorithms like KNN or KMeans.
SELECT ST_Distance(
			ST_Transform('SRID=4326;POINT(-72.1235 42.3521)'::geometry, 3857),
			ST_Transform('SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)'::geometry, 3857)
		);
st_distance
-----------------
167.441410065196

-- Geometry example - units in meters (SRID: 3857 as above, but corrected by cos(lat) to account for distortion)
SELECT ST_Distance(
			ST_Transform('SRID=4326;POINT(-72.1235 42.3521)'::geometry, 3857),
			ST_Transform('SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)'::geometry, 3857)
		) * cosd(42.3521);
st_distance
-----------------
123.742351254151

-- Geometry example - units in meters (SRID: 26986 Massachusetts state plane meters) (most accurate for Massachusetts)
SELECT ST_Distance(
			ST_Transform('SRID=4326;POINT(-72.1235 42.3521)'::geometry, 26986),
			ST_Transform('SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)'::geometry, 26986)
		);
st_distance
-----------------
123.797937878454

-- Geometry example - units in meters (SRID: 2163 US National Atlas Equal area) (least accurate)
SELECT ST_Distance(
			ST_Transform('SRID=4326;POINT(-72.1235 42.3521)'::geometry, 2163),
			ST_Transform('SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)'::geometry, 2163)
		);

st_distance
------------------
126.664256056812

Geography Examples

-- same as geometry example but note units in meters - use sphere for slightly faster less accurate
SELECT ST_Distance(gg1, gg2) As spheroid_dist, ST_Distance(gg1, gg2, false) As sphere_dist
FROM (SELECT
	'SRID=4326;POINT(-72.1235 42.3521)'::geography as gg1,
	'SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)'::geography as gg2
	) As foo  ;

  spheroid_dist   |   sphere_dist
------------------+------------------
 123.802076746848 | 123.475736916397

See Also

ST_3DDistance, ST_DWithin, ST_DistanceSphere, ST_DistanceSpheroid, ST_MaxDistance, ST_HausdorffDistance, ST_FrechetDistance, ST_Transform