This topic describes the ST_Distance function. This function calculates the 2D Euclidean distance between two geometry objects in the reference coordinate system of the geometry objects. If you specify two geography objects, this function returns the minimum spherical distance in meters between the geography objects.
Syntax
float ST_Distance(geometry g1 , geometry g2);
float ST_Distance(geography gg1 , geography gg2);
float ST_Distance(geography gg1 , geography gg2 , boolean useSpheroid);Parameters
| Parameter | Description |
|---|---|
| g1 | The first geometry object that you want to specify. |
| g2 | The second geometry object that you want to specify. |
| gg1 | The first geography object that you want to specify. |
| gg2 | The second geography object that you want to specify. |
| useSpheroid | Specifies whether to use an ellipsoid. The default is true, if you set this parameter to false, a specific precision is applied to improve the speed. |
Description
This function supports circular strings and curves.
Examples
The following example shows the difference between the ST_Distance function and the
ST_3DDistance function.
SELECT ST_Distance(g1,g2),ST_3DDistance(g1,g2) FROM(SELECT 'POINT(0 0 0)'::geometry as g1,
'POINT(1 1 1)'::geometry as g2) as test;
st_distance | st_3ddistance
-----------------+------------------
1.4142135623731 | 1.73205080756888
(1 row)