ST_Dimension
Name
ST_Dimension — Returns the topological dimension of a geometry.
Synopsis
integer
ST_Dimension
(
geometry
g
)
;
Description
Return the topological dimension of this Geometry object, which must
be less than or equal to the coordinate dimension. OGC SPEC
s2.1.1.1 - returns 0 for
POINT
, 1 for
LINESTRING
, 2 for
POLYGON
, and
the largest dimension of the components of a
GEOMETRYCOLLECTION
.
If the dimension is unknown (e.g. for an empty
GEOMETRYCOLLECTION
) 0 is returned.
This method implements the SQL/MM specification.
SQL-MM 3: 5.1.2
Enhanced: 2.0.0 support for Polyhedral surfaces and TINs was introduced. No longer throws an exception if given empty geometry.
![[Note]](https://access.crunchydata.com/documentation/postgis/latest/images/note.png)
|
|
|
Prior to 2.0.0, this function throws an exception if used with empty geometry. |
This function supports Polyhedral surfaces.
This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).
Examples
SELECT ST_Dimension('GEOMETRYCOLLECTION(LINESTRING(1 1,0 0),POINT(0 0))');
ST_Dimension
-----------
1
