PostGIS
Synopsis
geometry +`*`+ST_AddMeasure*(`geometry `geom_mline, float8
measure_start, float8 measure_end`)`;
Description
Return a derived geometry with measure values linearly interpolated between the start and end points. If the geometry has no measure dimension, one is added. If the geometry has a measure dimension, it is over-written with new values. Only LINESTRINGS and MULTILINESTRINGS are supported.
Availability: 1.5.0
This
function supports 3d and will not drop the z-index.
Examples
SELECT ST_AsText(ST_AddMeasure(
ST_GeomFromEWKT('LINESTRING(1 0, 2 0, 4 0)'),1,4)) As ewelev;
ewelev
--------------------------------
LINESTRINGM(1 0 1,2 0 2,4 0 4)
SELECT ST_AsText(ST_AddMeasure(
ST_GeomFromEWKT('LINESTRING(1 0 4, 2 0 4, 4 0 4)'),10,40)) As ewelev;
ewelev
----------------------------------------
LINESTRING(1 0 4 10,2 0 4 20,4 0 4 40)
SELECT ST_AsText(ST_AddMeasure(
ST_GeomFromEWKT('LINESTRINGM(1 0 4, 2 0 4, 4 0 4)'),10,40)) As ewelev;
ewelev
----------------------------------------
LINESTRINGM(1 0 10,2 0 20,4 0 40)
SELECT ST_AsText(ST_AddMeasure(
ST_GeomFromEWKT('MULTILINESTRINGM((1 0 4, 2 0 4, 4 0 4),(1 0 4, 2 0 4, 4 0 4))'),10,70)) As ewelev;
ewelev
-----------------------------------------------------------------
MULTILINESTRINGM((1 0 10,2 0 20,4 0 40),(1 0 40,2 0 50,4 0 70))ST_InterpolatePoint |
ST_IsValidTrajectory |