ST_Force3DZ

ST_Force3DZ returns a 3DZ geometry from the input geometry. For 2D geometries, the z coordinates of the nonempty points in the output geometry are all set to 0. For 3DM geometries, the geometry is projected on the xy-Cartesian plane, and the z coordinates of the nonempty points in the output geometry are all set to 0. For 3DZ geometries, a copy of the input geometry is returned. For 4D geometries, the geometry is projected to the xyz-Cartesian space. Empty points in the input geometry remain empty points in the output geometry.

Syntax

ST_Force3DZ(geom)

Arguments

geom

A value of data type GEOMETRY or an expression that evaluates to a GEOMETRY type.

Return type

GEOMETRY.

The spatial reference system identifier (SRID) value of the returned geometry is the SRID value of the input geometry.

If geom is null, then null is returned.

If geom is empty, then an empty geometry is returned.

Examples

The following SQL returns a 3DZ geometry from a 3DM geometry.

SELECT ST_AsEWKT(ST_Force3DZ(ST_GeomFromText('MULTIPOINT M(0 1 2, EMPTY, 2 3 4, 5 6 7)')));

st_asewkt
-----------
  MULTIPOINT Z ((0 1 0),EMPTY,(2 3 0),(5 6 0))