Hello, Unfortunatly, I don't find a way to print raster results in OpenJump. Can you explain me how I can do it ?
Thank you for your help ! Pierre Le lun. 20 juin 2016 à 16:16, Pierre Racine <pierre.rac...@sbf.ulaval.ca> a écrit : > I would try to understand, visually using OpenJump, how your tiles are > clipped in the two cases... I guess sometimes 1 pixel wide tiles get > clipped in a strange way. > > Pierre > > > -----Original Message----- > > From: postgis-users [mailto:postgis-users-boun...@lists.osgeo.org] On > Behalf > > Of Pierre Bails > > Sent: Wednesday, June 15, 2016 11:41 AM > > To: postgis-users@lists.osgeo.org > > Subject: [postgis-users] Raster tile size impact results > > > > 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
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