Thank you very much Pierre ! That's exactly what I was looking for. Sorry I didn't find the st_worldtorastercoord functions which do exactly what I need (maybe it should be a good idea to add a reference in the pixel accessors et setter functions -in "see also" - since theses function work at the pixel level).
Hugues. -----Message d'origine----- De : [email protected] [mailto:[email protected]] De la part de Pierre Racine Envoyé : vendredi 5 avril 2013 18:12 À : PostGIS Users Discussion Objet : Re: [postgis-users] How to perform st_PixelAsPolygon(rast, geom) ? You can do: SELECT ST_PixelAsPolygon(rast, ST_WorldToRasterCoordX(rast, ST_X(geom)), ST_WorldToRasterCoordY(rast, ST_Y(geom))) geom FROM yourrast, yourpoints WHERE ST_Intersects(rast, geom) Note that PixelAsPolygon has no "s". You will get the vectorization of every pixels having a point inside. Up to you to deal with duplicates. Pierre > -----Original Message----- > From: [email protected] [mailto:postgis-users- > [email protected]] On Behalf Of Hugues François > Sent: Friday, April 05, 2013 6:51 AM > To: [email protected] > Subject: [postgis-users] How to perform st_PixelAsPolygon(rast, geom) ? > > Hello, > > > > I need to work with a dem raster at the pixel scale but there are few > functions to access them. Maybe I forgot something but, if we can have > a value crossing a point with raster using st_value, we can't access > the pixel geometry directly from a point. > > > > The only way I found was first to use St_PixelAsPolygons to access > pixel geometry (for relevant tiles) and then intersects resulting > geometries with original points but this method costs very much. > > > > Anyone have an idea to increase performances ? > > > > Hugues. _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
