Why not? This is what ST_Box2D() does and ST_Envelope() returns exactly the same values...
But again: Is there a non aggregate function which returns the exact extent (float8s) of a geometry? If not, why not? Pierre >-----Original Message----- >From: [email protected] [mailto:postgis-users- >[email protected]] On Behalf Of Mark Cave-Ayland >Sent: 17 décembre 2009 05:22 >To: PostGIS Users Discussion >Subject: Re: [postgis-users] Getting the exact extent of a geometry > >Pierre Racine wrote: > >> Hi, >> >> ST_Envelope(geometry) returns a kind of degenerated version (float4s instead >> of float8s) of the >extent of a geometry based on the cached BOX2D and ST_Extent(geometry) is an >aggregate. >> >> Is there a non aggregate function which returns the exact extent (float8s) >> of a geometry? >> >> Try: >> >> SELECT ST_AsText(ST_Envelope('LINESTRING(0 0, 1.00000000000001 >> 1)'::geometry)) >> UNION ALL >> SELECT ST_AsText(ST_Box2D('LINESTRING(0 0, 1.00000000000001 1)'::geometry)) >> UNION ALL >> SELECT ST_AsText(ST_Extent('LINESTRING(0 0, 1.00000000000001 1)'::geometry)); >> >> Thanks, >> >> Pierre > >Uggg. Nothing should *ever* return the contents of a BOX2DFLOAT4 back to >the user. If ST_Envelope() does, then this is definitely a bug. > > >ATB, > >Mark. > >-- >Mark Cave-Ayland - Senior Technical Architect >PostgreSQL - PostGIS >Sirius Corporation plc - control through freedom >http://www.siriusit.co.uk >t: +44 870 608 0063 > >Sirius Labs: http://www.siriusit.co.uk/labs >_______________________________________________ >postgis-users mailing list >[email protected] >http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
