ST_Value and ST_DumpAsPolygons do very different things. ST_Value gets a value for a specific pixel while ST_DumpAsPolygons() dumps values by merging pixels with same value in an area.
-bborie On Thu, Jun 6, 2013 at 12:38 PM, Jean Marchal <jean.d.marc...@gmail.com>wrote: > Dear List, > > value's number 4 in this raster come out with ST_Value: > > SELECT ST_Value(rast, 1, 8, 2), ST_BandnoDataValue(rast), > ST_BandPixelType(rast) > FROM (SELECT ' > 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'::raster > rast) foo > > but not with ST_DumpAsPolygons: > > SELECT (ST_DumpAsPolygons(rast)).val > FROM (SELECT > '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'::raster > rast) foo > > Is this a bug or I am doing something wrong ? > > Thanks, > > Jean > > > -- > Jean Marchal > > Etudiant au doctorat / PHD student > Université Laval - Pavillon Abitibi-Price > Faculté de foresterie, de géographie et de géomatique > 2405, rue de la Terrasse > Québec (Québec) G1V 0A6 > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > >
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