[Geotools-gt2-users] ST_Intersects checks for contains? From: Chad S - 2011-04-28 19:28:52 Attachments: Message as HTML ```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 ```
 Re: [Geotools-gt2-users] ST_Intersects checks for contains? From: Jody Garnett - 2011-04-28 23:36:55 Attachments: Message as HTML ```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); ) 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. Jody On Fri, Apr 29, 2011 at 5:28 AM, Chad S 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 > > > ------------------------------------------------------------------------------ > WhatsUp Gold - Download Free Network Management Software > The most intuitive, comprehensive, and cost-effective network > management toolset available today. Delivers lowest initial > acquisition cost and overall TCO of any competing solution. > http://p.sf.net/sfu/whatsupgold-sd > _______________________________________________ > Geotools-gt2-users mailing list > Geotools-gt2-users@... > https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users > > ```