PostGIS
Name
ST_Relate — Tests if two geometries have a topological relationship matching an Intersection Matrix pattern, or computes their Intersection Matrix
Synopsis
+boolean +ST_Relate(+`geometry `+geomA, geometry geomB,
text intersectionMatrixPattern`)`;
+text +ST_Relate(+`geometry `+geomA, geometry
geomB`)`;
+text +ST_Relate(+`geometry `+geomA, geometry geomB,
integer boundaryNodeRule`)`;
Description
These functions allow testing and evaluating the spatial (topological) relationship between two geometries, as defined by the Dimensionally Extended 9-Intersection Model (DE-9IM).
The DE-9IM is specified as a 9-element matrix indicating the dimension
of the intersections between the Interior, Boundary and Exterior of two
geometries. It is represented by a 9-character text string using the
symbols 'F', '0', '1', '2' (e.g. 'FF1FF0102').
A specific kind of spatial relationships is evaluated by comparing the
intersection matrix to an intersection matrix pattern. A
pattern can include the additional symbols 'T' and '*'. Common spatial
relationships are provided by the named functions
ST_Contains,
ST_ContainsProperly,
ST_Covers, ST_CoveredBy,
ST_Crosses, ST_Disjoint,
ST_Equals, ST_Intersects,
ST_Overlaps, ST_Touches,
and ST_Within. Using an explicit pattern allows
testing multiple conditions of intersects, crosses, etc in one step. It
also allows testing spatial relationships which do not have a named
spatial relationship function. For example, the relationship
"Interior-Intersects" has the DE-9IM pattern T********, which is not
evaluated by any named predicate.
For more information refer to Section 5.1, “Determining Spatial Relationships”.
Variant 1: Tests if two geometries are spatially related
according to the given intersectionMatrixPattern.
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Variant 2: Returns the DE-9IM matrix string for the spatial relationship between the two input geometries. The matrix string can be tested for matching a DE-9IM pattern using ST_RelateMatch.
Variant 3: Like variant 2, but allows specifying a
Boundary Node Rule. A boundary node rule allows finer control
over whether geometry boundary points are considered to lie in the
DE-9IM Interior or Boundary. The boundaryNodeRule code is: 1:
OGC/MOD2, 2: Endpoint, 3: MultivalentEndpoint, 4: MonovalentEndpoint.
This function is not in the OGC spec, but is implied. see s2.1.13.2
This method
implements the OGC Simple
Features Implementation Specification for SQL 1.1. s2.1.1.2 //
s2.1.13.3
This method
implements the SQL/MM specification. SQL-MM 3: 5.1.25
Performed by the GEOS module
Enhanced: 2.0.0 - added support for specifying boundary node rule.
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Examples
Using the boolean-valued function to test spatial relationships.
SELECT ST_Relate('POINT(1 2)', ST_Buffer( 'POINT(1 2)', 2), '0FFFFF212');
st_relate
-----------
t
SELECT ST_Relate(POINT(1 2)', ST_Buffer( 'POINT(1 2)', 2), '*FF*FF212');
st_relate
-----------
tTesting a custom spatial relationship pattern as a query condition, with
&& to enable using a spatial index.
-- Find compounds that properly intersect (not just touch) a poly (Interior Intersects)
SELECT c.* , p.name As poly_name
FROM polys AS p
INNER JOIN compounds As c
ON c.geom && p.geom
AND ST_Relate(p.geom, c.geom,'T********');Computing the intersection matrix for spatial relationships.
SELECT ST_Relate( 'POINT(1 2)',
ST_Buffer( 'POINT(1 2)', 2));
st_relate
-----------
0FFFFF212
SELECT ST_Relate( 'LINESTRING(1 2, 3 4)',
'LINESTRING(5 6, 7 8)' );
st_relate
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FF1FF0102See Also
Section 5.1, “Determining Spatial Relationships”, ST_RelateMatch, ST_Contains, ST_ContainsProperly, ST_Covers, ST_CoveredBy, ST_Crosses, ST_Disjoint, ST_Equals, ST_Intersects, ST_Overlaps, ST_Touches, ST_Within
ST_Overlaps |
ST_RelateMatch |