RE: [postgis-users] about st_distancethanks , Regina ----- Original Message ----- From: Obe, Regina To: PostGIS Users Discussion Sent: Friday, October 03, 2008 7:49 PM Subject: RE: [postgis-users] about st_distance
Francisco, ST_Distance (you can think of as min distance) returns the shortest distance between 2 geometries. So between a point and a poly, if the point is in the poly the distance will be 0, it its outside it would be the distance between the closest point on the surface of the poly and the point. (there is actually another distance which no one asks about ST_MaxDistance - which is between the most distant point of a poly to a point - anyway I just mention it, but you wouldn't want to use it here). Your below query won't use indexes since ST_Distance doesn't use an index. Use ST_Dwithin instead SELECT p.gid as id_parcela,tipo as tipo_Pozo FROM selepozo(1,1) po,parcelas p WHERE ST_DWithin(p.the_geom, po.the_geom, 1) http://postgis.refractions.net/documentation/manual-svn/ST_DWithin.html Hope that helps, Regina -----Original Message----- From: [EMAIL PROTECTED] on behalf of fsalas Sent: Fri 10/3/2008 7:01 AM To: [email protected] Subject: [postgis-users] about st_distance Hi, I need to know about obtain distance between polygon( parcels) and point I Use the next sentences SELECT p.gid as id_parcela,tipo as tipo_Pozo FROM selepozo(1,1) po,parcelas p WHERE ST_distance(p.the_geom, po.the_geom) < 1 I have some questions This distance is between centroide of parcels to point or between border of parcels to point ? Best Regards, Francisco Salas ___________________________________ Dpto de Sistemas Informáticos Oficina Central Grupo Empresarial GEOCUBA Este mensaje esta libre de virus. Revisado por Kaspersky Antivirus ---------------------------------------------------------------------- Engine version: 4.0.1.14 Engine date: 2002/06/25 Definition count: 1148493 Definition date: 2008/10/03 MDAV version: 2.2.8 ------------------------------------------------------------------------------ The substance of this message, including any attachments, may be confidential, legally privileged and/or exempt from disclosure pursuant to Massachusetts law. It is intended solely for the addressee. If you received this in error, please contact the sender and delete the material from any computer. ------------------------------------------------------------------------------ Help make the earth a greener place. If at all possible resist printing this email and join us in saving paper. ------------------------------------------------------------------------------ _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users ___________________________________ Dpto de Sistemas Informáticos Oficina Central Grupo Empresarial GEOCUBA Este mensaje esta libre de virus. Revisado por Kaspersky Antivirus ---------------------------------------------------------------------- Engine version: 4.0.1.14 Engine date: 2002/06/25 Definition count: 1156750 Definition date: 2008/10/06 MDAV version: 2.2.8
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