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i am using gdal 1.10 and 2.1.1. i have a VRT datasource in WGS84 where i forced the corner coordinates to the min/max values of EPSG:3857 (-180,85.5,180,-85.5). gdalinfo output for this VRT looks like this: Size is 1296001, 601200 Coordinate System is: GEOGCS["WGS 84", DATUM["WGS_1984", SPHEROID["WGS 84",6378137,298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4326"]] Origin = (-180.000000000000000,85.500000000000000) Pixel Size = (0.000277777563443,-0.000284431137725) Corner Coordinates: Upper Left (-180.0000000, 85.5000000) (180d 0' 0.00"W, 85d30' 0.00"N) Lower Left (-180.0000000, -85.5000000) (180d 0' 0.00"W, 85d30' 0.00"S) Upper Right ( 180.0000000, 85.5000000) (180d 0' 0.00"E, 85d30' 0.00"N) Lower Right ( 180.0000000, -85.5000000) (180d 0' 0.00"E, 85d30' 0.00"S) Center ( 0.0000000, -0.0000000) ( 0d 0' 0.01"E, 0d 0' 0.00"S) Band 1 Block=128x128 Type=Int16, ColorInterp=Gray Basically, i have the world minus the poles. Now i want to convert this to EPSG:3857. I use gdalwarp for this, using bilinear interpolation: ./gdalwarp -of VRT -co TILED=YES -srcnodata 9999 -t_srs 'EPSG:3785' -multi wgs84.vrt wmerc.vrt -overwrite -r bilinear running gdalinfo on wmerc then gives this: Size is 995026, 1025175 Coordinate System is: PROJCS["Popular Visualisation CRS / Mercator (deprecated)", GEOGCS["Popular Visualisation CRS", DATUM["Popular_Visualisation_Datum", SPHEROID["Popular Visualisation Sphere",6378137,0, AUTHORITY["EPSG","7059"]], TOWGS84[0,0,0,0,0,0,0], AUTHORITY["EPSG","6055"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9122"]], AUTHORITY["EPSG","4055"]], PROJECTION["Mercator_1SP"], PARAMETER["central_meridian",0], PARAMETER["scale_factor",1], PARAMETER["false_easting",0], PARAMETER["false_northing",0], UNIT["metre",1, AUTHORITY["EPSG","9001"]], AXIS["X",EAST], AXIS["Y",NORTH], EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"], AUTHORITY["EPSG","3785"]] Origin = (-20037508.342789247632027,20644642.363762538880110) Pixel Size = (40.275313937642778,-40.275354414328227) Corner Coordinates: Upper Left (-20037508.343,20644642.364) (180d 0' 0.00"E, 85d28'11.27"N) Lower Left (-20037508.343,-20644644.098) (180d 0' 0.00"E, 85d28'11.28"S) Upper Right (20037476.183,20644642.364) (179d59'58.96"E, 85d28'11.27"N) Lower Right (20037476.183,-20644644.098) (179d59'58.96"E, 85d28'11.28"S) Center ( -16.0797308, -0.8670919) ( 0d 0' 0.52"W, 0d 0' 0.03"S) Band 1 Block=512x128 Type=Int16, ColorInterp=Gray NoData Value=9999 Note that the corner coordinates for upper/lower left look correct, but the corner coordinates for upper/lower right (the longitude) is missing is missing 32 units. Broadly put, i am missing a sliver on the right side, but only in regards to the coordinates. The data is there, but the coordinates to the right seem wrong. Why is that? i could just modify the coordinates to match the world (longitudinal) using gdal_translate but i fear i am overlooking something else here which might just come back to bite me. Bet regards, Oliver
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