Description

Returns TRUE if the LINESTRING's start and end points are coincident. For Polyhedral Surfaces, reports if the surface is areal (open) or volumetric (closed).

This method implements the OGC Simple Features Implementation Specification for SQL 1.1.

This method implements the SQL/MM specification. SQL-MM 3: 7.1.5, 9.3.3

	SQL-MM defines the result of ST_IsClosed(NULL) to be 0, while PostGIS returns NULL.

This function supports 3d and will not drop the z-index.

This method supports Circular Strings and Curves.

Enhanced: 2.0.0 support for Polyhedral surfaces was introduced.

This function supports Polyhedral surfaces.

Line String and Point Examples

SELECT ST_IsClosed('LINESTRING(0 0,1 1)'::geometry);

f

Figure

SELECT ST_IsClosed('LINESTRING(0 0,0 1,1 1,0 0)'::geometry);

t

Figure

SELECT ST_IsClosed('MULTILINESTRING((0 0,0 1,1 1,0 0),(0 0,1 1))'::geometry);

f

Figure

SELECT ST_IsClosed('POINT(0 0)'::geometry);

t

SELECT ST_IsClosed('MULTIPOINT((0 0),(1 1))'::geometry);

t

Polyhedral Surface Examples

This example uses a cube.

SELECT ST_IsClosed('POLYHEDRALSURFACE( ((0 0 0,0 0 1,0 1 1,0 1 0,0 0 0)),
((0 0 0,0 1 0,1 1 0,1 0 0,0 0 0)),((0 0 0,1 0 0,1 0 1,0 0 1,0 0 0)),
((1 1 0,1 1 1,1 0 1,1 0 0,1 1 0)),
((0 1 0,0 1 1,1 1 1,1 1 0,0 1 0)),((0 0 1,1 0 1,1 1 1,0 1 1,0 0 1)) )');

t

Figure

This example uses the same cube with one side missing.

SELECT ST_IsClosed('POLYHEDRALSURFACE( ((0 0 0,0 0 1,0 1 1,0 1 0,0 0 0)),
       ((0 0 0,0 1 0,1 1 0,1 0 0,0 0 0)),((0 0 0,1 0 0,1 0 1,0 0 1,0 0 0)),
       ((1 1 0,1 1 1,1 0 1,1 0 0,1 1 0)),
       ((0 1 0,0 1 1,1 1 1,1 1 0,0 1 0)) )');

f

Figure

See Also

ST_IsRing