I always under stood it as "not disjoint".
You can however check the jts javadocs; they provide a definition in terms
of the "relate" function:
http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/geom/Geometry.html#intersects(com.vividsolutions.jts.geom.Geometry)
The intersects predicate has the following equivalent definitions:
- The two geometries have at least one point in common
- The DE-9IM Intersection Matrix for the two geometries matches at least
one of the patterns
- [T********]
- [*T*******]
- [***T*****]
- [****T****]
- ! g.disjoint(this) = true
(intersects is the inverse of disjoint)
Within has the following:
The within predicate has the following equivalent definitions:
- Every point of this geometry is a point of the other geometry, and the
interiors of the two geometries have at least one point in common.
- The DE-9IM Intersection Matrix for the two geometries matches
[T*F**F***]
- g.contains(this) = true
(within is the converse of
contains(com.vividsolutions.jts.geom.Geometry)<http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/geom/Geometry.html#contains(com.vividsolutions.jts.geom.Geometry)>
)
<http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/geom/Geometry.html#intersects(com.vividsolutions.jts.geom.Geometry)>Background
information here:
http://docs.geotools.org/latest/userguide/library/jts/dim9.html
My take on it is that intersects and within can both be true at the same
time; and that within implies intersects (but not the other way).
The "clear part of this" is comparing:
* intersects: [T********]
* withing: [T*F**F***]
The first relationship about the interiors touching is a case where within
and intersects test the same condition.
<http://docs.geotools.org/latest/userguide/library/jts/dim9.html>Jody
On Fri, Apr 29, 2011 at 5:28 AM, Chad S <[email protected]> wrote:
> ive been doing manual queries and the documentation between intersects,
> contains and within don't seem to clearly say whether or not ST_Intersects
> inherently checks for contains. would love to get a confirmation on that.
> thanks!
>
> chad
>
>
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