Hi all, I'm looking for get all pixel's value in a raster insert thanks to raster2pgsql intersect by a polygon. Nevertheless, there are some things that I don't understand: depends on tile size, I don't have the same result... The error between 2 raster is also correlate to the pixel size (I assume it's due to the pixel number).
Can you explain me how the tile size can influence the final result ? *Here is the query :* SELECT DISTINCT SUM((px).val) FROM( SELECT * FROM mns INNER JOIN st_setsrid(st_geomfromgeojson('{"type":"Polygon","coordinates":[[[x,y], [x,y],[x,y] ]]}'), 4326) as geom on ST_Intersects(mns.rast, geom) ) AS clip, ST_PixelAsCentroids (ST_Clip(clip.rast, clip.geom),1) AS px; *DSM px size 70cm: * raster2pgsql -a -t 250x250 -s 4326 -F pathToDSM.tiff dsmTable (result: 46 347 846) raster2pgsql -a -t 50x50 -s 4326 -F pathToDSM.tiff dsmTable : 46 382 873 Difference: 35027 *DSM px size 20cm : * raster2pgsql -a -t 250x250 -s 4326 -F pathToDSM.tiff dsmTable : 567 505 888 raster2pgsql -a -t 50x50 -s 4326 -F pathToDSM.tiff dsmTable : 596 897 610 Difference: 29 391 722 If we considere 250x250's result as reference, there is a difference of 0.07% in the first case, and 5% in the second. If the polygon area increases, the error rate increases. Thank you, Pierre
_______________________________________________ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/postgis-users