Briefly the ST_Intersection(rast, geom) vectorize the raster in order to make a standard vector/vector intersection afterward. Since vectorizing is a slow process, a query involving ST_Intersection() is always more efficient with smaller tiles.
Pierre > -----Original Message----- > From: [email protected] [mailto:postgis-users- > [email protected]] On Behalf Of Joan > Sent: Tuesday, November 08, 2011 11:56 AM > To: PostGIS Users Discussion > Subject: Re: [postgis-users] Tiles > > Yes, I have been doing an analysis with the same raster file but different > tile sizes > and I get different results e.g st_intersects(rast, geom) . I would like to > know > what the tile size has to do with the query results or performance. > > > > On 8 November 2011 17 <tel:2011%2017> :30, Pierre Racine > <[email protected]> wrote: > > > I guess you mean "raster tile"? > > > -----Original Message----- > > From: [email protected] [mailto:postgis- > users- > > [email protected]] On Behalf Of Joan > > Sent: Tuesday, November 08, 2011 10 <tel:2011%2010> :19 AM > > To: PostGIS Users Discussion > > Subject: [postgis-users] Tiles > > > > > Hello, > > > > I would like to know what the idea behind tiles is. > > > > Regards > > > > Joan M > > _______________________________________________ > 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
