Name
ST_ClosestPoint — Returns the 2D point on g1 that is closest to g2. This is the first point of the shortest line from one geometry to the other.
Synopsis
geometry ST_ClosestPoint(geometry
geom1, geometry
geom2);
geography ST_ClosestPoint(geography
geom1, geography
geom2, boolean
use_spheroid = true);
Description
Returns the 2-dimensional point on geom1 that is closest to geom2.
This is the first point of the shortest line between the geometries
(as computed by ST_ShortestLine).
![[Note]](../images/note.png)
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If you have a 3D Geometry, you may prefer to use ST_3DClosestPoint. |
Enhanced: 3.4.0 - Support for geography.
Availability: 1.5.0
Examples
The closest point for a Point and a LineString is the point itself. The closest point for a LineString and a Point is a point on the line.
SELECT ST_ClosestPoint(pt, line) AS cp_pt_line, ST_ClosestPoint(line, pt) AS cp_line_pt
FROM (SELECT 'POINT (160 40)'::geometry AS pt,
'LINESTRING (10 30,50 50,30 110,70 90,180 140,130 190)'::geometry AS line ) AS t;
cp_pt_line | cp_line_pt ----------------+------------------------------------------ POINT(160 40) | POINT(125.75342465753425 115.34246575342466)
Find the closest point on polygon A to polygon B.
WITH source AS (
SELECT 'POLYGON ((190 150,20 10,160 70,190 150))'::geometry AS a,
ST_Buffer('POINT(80 160)'::geometry, 30) AS b
)
SELECT b AS polygon_b,
ST_ClosestPoint(a, b) AS closest_point
FROM source;
POLYGON((110 160,109.424 154.147,107.716 148.519,104.944 143.333,101.213 138.787,96.667 135.056,91.481 132.284,85.853 130.576,80 130,74.147 130.576,68.519 132.284,63.333 135.056,58.787 138.787,55.056 143.333,52.284 148.519,50.576 154.147,50 160,50.576 165.853,52.284 171.481,55.056 176.667,58.787 181.213,63.333 184.944,68.519 187.716,74.147 189.424,80 190,85.853 189.424,91.481 187.716,96.667 184.944,101.213 181.213,104.944 176.667,107.716 171.481,109.424 165.853,110 160)) | POINT(131.59149149528952 101.89887534906195)