ST_ClosestPoint

Introduction: Returns the 2-dimensional point on geom1 that is closest to geom2. This is the first point of the shortest line between the geometries. If using 3D geometries, the Z coordinates will be ignored. If you have a 3D Geometry, you may prefer to use ST_3DClosestPoint. It will throw an exception indicates illegal argument if one of the params is an empty geometry.

Format: ST_ClosestPoint(g1: Geometry, g2: Geometry)

SQL Example:

SELECT ST_AsText( ST_ClosestPoint(g1, g2)) As ptwkt;

Input: g1: POINT (160 40), g2: LINESTRING (10 30, 50 50, 30 110, 70 90, 180 140, 130 190)

Output: POINT(160 40)

Input: g1: LINESTRING (10 30, 50 50, 30 110, 70 90, 180 140, 130 190), g2: POINT (160 40)

Output: POINT(125.75342465753425 115.34246575342466)

Input: g1: 'POLYGON ((190 150, 20 10, 160 70, 190 150))', g2: ST_Buffer('POINT(80 160)', 30)

Output: POINT(131.59149149528952 101.89887534906197)