ST_Force4D - Amazon Redshift
SyntaxArgumentsReturn typeExamples
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ST_Force4D

ST_Force4D returns a 4D geometry of the input geometry. For 2D geometries, the z and m coordinates of the nonempty points in the output geometry are all set to 0. For 3DM geometries, the z coordinates of the nonempty points in the output geometry are all set to 0. For 3DZ geometries, the m coordinates of the nonempty points in the output geometry are all set to 0. For 4D geometries, a copy of the input geometry is returned. Empty points in the input geometry remain empty points in the output geometry.

Syntax

ST_Force4D(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 4D geometry from a 3DM geometry. 

SELECT ST_AsEWKT(ST_Force4D(ST_GeomFromText('MULTIPOINT M(0 1 2, EMPTY, 2 3 4, 5 6 7)')));

st_asewkt
-----------
  MULTIPOINT ZM ((0 1 0 2),EMPTY,(2 3 0 4),(5 6 0 7))