ST_Crosses method for type ST

ST_Crosses method for type ST_Geometry

Tests if a geometry value crosses another geometry value.

Syntax

geometry-expression.ST_Crosses(geo2)

Parameters

Name	Type	Description
geo2	ST_Geometry	The other geometry value that is to be compared to the geometry-expression.

Returns

BIT Returns 1 if the geometry-expression crosses geo2, otherwise 0. Returns NULL if geometry-expression is a surface or multisurface if or geo2 is a point or multipoint.

Remarks

Tests if a geometry value crosses another geometry value.

When both geometry-expression and geo2 are curves or multicurves, they cross each other if their interiors intersect at one or more points. If the intersection results in a curve or multicurve, the geometries do not cross. If all of the intersecting points are boundary points, the geometries do not cross.

When geometry-expression has lower dimension than geo2, then geometry-expression crosses geo2 if part of geometry-expression is on the interior of geo2 and part of geometry-expression is on the exterior of geo2.

More precisely, geometry-expression.ST_Crosses( geo2 ) returns 1 when the following is TRUE:

( geometry-expression.ST_Dimension() = 1
  AND geo2.ST_Dimension() = 1
  AND geometry-expression.ST_Relate( geo2, '0********' ) = 1 )
OR( geometry-expression.ST_Dimension() < geo2.ST_Dimension()
  AND geometry-expression.ST_Relate( geo2, 'T*T******' ) = 1 )

Note

If the geometry-expression contains circular strings, then these are interpolated to line strings.

Note

This method can not be used with geometries in round-Earth spatial reference system.

Standards and compatibility

Example

The following example returns the result 1.

SELECT NEW ST_LineString( 'LineString( 0 0, 2 2 )' )
        .ST_Crosses( NEW ST_LineString( 'LineString( 0 2, 2 0 )' ) )

The following examples returns the result 0 because the interiors of the two lines do not intersect (the only intersection is at the first linestring boundary).

SELECT NEW ST_LineString( 'LineString( 0 1, 2 1 )' )
        .ST_Crosses( NEW ST_LineString( 'LineString( 0 0, 2 0 )' ) )

The following example returns NULL because the first geometry is a surface.

SELECT NEW ST_Polygon( 'Polygon(( 0 0, 0 1, 1 0, 0 0))' )
        .ST_Crosses( NEW ST_LineString( 'LineString( 0 0, 2 0 )' ) )

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