ro ro en en en fa en ceb en en en en en en en en en en en en en en en en en en en en en sl en en
Returns a point interpolated along a line at a fractional location. First argument must be a LINESTRING. Second argument is a float between 0 and 1 representing the fraction of line length where the point is to be located. The Z and M values are interpolated if present.
See ST_LineLocatePoint for computing the line location nearest to a Point.
This function computes points in 2D and then interpolates values for Z and M, while ST_3DLineInterpolatePoint computes points in 3D and only interpolates the M value.
Since release 1.1.1 this function also interpolates M and Z values (when present), while prior releases set them to 0.0.
Availability: 0.8.2, Z and M supported added in 1.1.1
Changed: 2.1.0. Up to 2.0.x this was called ST_Line_Interpolate_Point.
This function supports 3d and will not drop the z-index.
A LineString with the interpolated point at 20% position (0.20)
-- The point 20% along a line SELECT ST_AsEWKT( ST_LineInterpolatePoint( 'LINESTRING(25 50, 100 125, 150 190)', 0.2 )); ---------------- POINT(51.5974135047432 76.5974135047432)
The mid-point of a 3D line:
SELECT ST_AsEWKT( ST_LineInterpolatePoint(' LINESTRING(1 2 3, 4 5 6, 6 7 8)', 0.5 )); -------------------- POINT(3.5 4.5 5.5)
The closest point on a line to a point:
SELECT ST_AsText( ST_LineInterpolatePoint( line.geom, ST_LineLocatePoint( line.geom, 'POINT(4 3)'))) FROM (SELECT ST_GeomFromText('LINESTRING(1 2, 4 5, 6 7)') As geom) AS line; ------------ POINT(3 4)