Name

ST_IsSimple — Tests if a geometry has no points of self-intersection or self-tangency.

Synopsis

boolean ST_IsSimple(geometry geomA);

Description

Returns true if this Geometry has no anomalous geometric points, such as self-intersection or self-tangency. For more information on the OGC's definition of geometry simplicity and validity, refer to "Ensuring OpenGIS compliance of geometries"

[Note]

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

This method implements the OGC Simple Features Implementation Specification for SQL 1.1. s2.1.1.1

This method implements the SQL/MM specification. SQL-MM 3: 5.1.8

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

Examples

Code
SELECT ST_IsSimple('POLYGON((1 2,3 4,5 6,1 2))');
Output
f
Figure
Geometry figure for visual-st-issimple-01
Code
SELECT ST_IsSimple('LINESTRING(1 1,2 2,2 3.5,1 3,1 2,2 1)');
Output
f
Figure
Geometry figure for visual-st-issimple-02

See Also

ST_IsValid