> Hi. > I'm, having a problem with some geometries. > I have buildings and blocks represented by polygons, and I have to check > if buildings are contained in blocks. > > The problem is that buildings that are snapped to blocks sides, aren't > considered inside the block. > > These are the validations that I've used so far. > > ST_Covers(block, building) => false > ST_Contains(block, building) => false > ST_Coveredby(building, block) => false > ST_Within(building, block) => false > > > The following validations are the ones that confuses me. > > ST_Covers(ST_intersection(block, building), building) => true > ST_Intersection(block, building) = building => true > ST_isEmpty(ST_Difference(building, block)) => true > > For what I've read, here > http://lin-ear-th-inking.blogspot.com/2007/06/subtleties-of-ogc-covers-spatial.html > "Geometry A covers Geometry B if no points of B lie in the exterior of > A" > Covers should return true. > > The environment is: > SELECT version(); => "PostgreSQL 8.4.4 on x86_64-pc-linux-gnu, compiled > by GCC gcc-4.3.real (Debian 4.3.2-1.1) 4.3.2, 64-bit" > > SELECT postgis_version(); => "1.5 USE_GEOS=1 USE_PROJ=1 USE_STATS=1" > > I've attached two geometries that you can use to check if I'm doing > something wrong. > > Thanks for your time. > --
Hi, For this kind of relationship, st_relate is very powerful: a good explanation is given here: http://2007.foss4g.org/presentations/view.php?abstract_id=117 along with a concrete example that, if I recall correctly, is pretty much the same as yours. Nicolas _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
