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]](../images/note.png)
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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
SELECT ST_IsSimple(ST_GeomFromText('POLYGON((1 2, 3 4, 5 6, 1 2))'));
st_issimple
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f
(1 row)
SELECT ST_IsSimple(ST_GeomFromText('LINESTRING(1 1,2 2,2 3.5,1 3,1 2,2 1)'));
st_issimple
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f
(1 row)