ST_Force3DM

Signature

GEOMETRY ST_Force3DM(GEOMETRY geom);
GEOMETRY ST_Force3DM(GEOMETRY geom, DOUBLE mValue);

Description

Forces a geometry geom to be in XYM mode.

If geom has no M component, then a M value is tacked on.

User can set a default M value (mValue). If not specified, mValue is set to zero.

If geom has already a Z value, then it is removed.

Already XYM geometries are returned untouched.

Examples

No effect on `XYM` geometries

SELECT ST_Force3DM('POINT M(-10 10 6)');
-- Answer:          POINT M(-10 10 6)

Adding `M` dimension

SELECT ST_Force3DM('POINT(-10 10)');
-- Answer:          POINT M(-10 10 0)

SELECT ST_Force3DM('LINESTRING(-10 10, 10 10)');
-- Answer:          LINESTRING M(-10 10 0, 10 10 0)

SELECT ST_Force3DM('GEOMETRYCOLLECTION(
                        POINT(1 1), 
                        LINESTRING(-10 10, 10 10), 
                        POLYGON((2 2, 10 0, 10 5, 0 5, 2 2)))');
-- Answer:          GEOMETRYCOLLECTION M (
--                      POINT M (1 1 0), 
--                      LINESTRING M (-10 10 0, 10 10 0), 
--                      POLYGON M ((2 2 0, 10 0 0, 10 5 0, 0 5 0, 2 2 0)))

Specifying `mValue`

SELECT ST_Force3DM('POLYGON((2 2, 10 0, 10 5, 0 5, 2 2))', 5);
-- Answer:          POLYGON M((2 2 5, 10 0 5, 10 5 5, 0 5 5, 2 2 5))

SELECT ST_Force3DM('MULTIPOINT((2 2), (10 0))', 5);
-- Answer:          MULTIPOINT M ((2 2 5), (10 0 5))

Removing `Z` dimension and adding the `M` one

SELECT ST_Force3DM('POINT Z(-10 10 12)',10);
-- Answer:          POINT M(-10 10 10)

SELECT ST_Force3DM('LINESTRING Z(-10 10 4, 10 10 6)', 3);
-- Answer:          LINESTRING M(-10 10 3, 10 10 3)

SELECT ST_Force3DM('POLYGON Z((2 2 4, 10 0 3, 10 5 2, 0 5 1, 2 2 4))', 5);
-- Answer:          POLYGON M((2 2 5, 10 0 5, 10 5 5, 0 5 5, 2 2 5))

See also