The ST_Is3D() function

The SE_Is3d() function returns t (TRUE) if the ST_Geometry object has three-dimensional coordinates; otherwise, returns f (FALSE).

Properties of geometries are described in Properties of spatial data types.

Syntax

ST_Is3D(g1 ST_Geometry)

Return type

BOOLEAN

Example

The threed_test table is created with INTEGER gid and g1 ST_Geometry columns:

CREATE TABLE threed_test (gid   smallint,
                          g1    ST_Geometry);

The following INSERT statements insert two points into the threed_test table. The first point does not contain Z coordinates, while the second does:

INSERT INTO threed_test VALUES(
   1, ST_PointFromText('point (10 10)',1000)
);

INSERT INTO threed_test VALUES(
   1, ST_PointFromText('point z(10.92 10.12 5)',1000)
);

The query lists the contents of the gid column with the results of the SE_Is3d function. The function returns a 0 for the first row, which does not have a Z coordinate, and a 1 for the second row, which does:

SELECT gid, ST_Is3D (g1) is_it_3d from threed_test;

   gid is_it_3d 

     1        f
     1        t