id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc 5273,GTiff Output Mercator Corner Coordinates Error using 1.10.1,itbeyond,warmerdam,"I am using Mapserver to generate GTiff files using the following: {{{ PROJECTION ""init=epsg:3857"" END OUTPUTFORMAT NAME ""GTiff"" DRIVER GDAL/GTiff MIMETYPE ""image/tiff"" IMAGEMODE RGB FORMATOPTION ""COMPRESS=LZW"" END }}} When I create a map it works as expected however upon looking at the gdalinfo I notice the coordinates for the map corners are correct in the DMS but wrong in the Mercator as per this (using gdal 1.10.1 and Mapserver 6.4.0): {{{ Driver: GTiff/GeoTIFF Files: mapserv.tiff Size is 1000, 1000 Coordinate System is: PROJCS[""WGS 84 / Pseudo-Mercator"", 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""]], 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""]], 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"",""3857""]] Origin = (12889228.989798404000000,-3724386.063095235300000) Pixel Size = (25.399986284008403,-25.399986284008403) Metadata: AREA_OR_POINT=Area TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) TIFFTAG_XRESOLUTION=200 TIFFTAG_YRESOLUTION=200 Image Structure Metadata: COMPRESSION=LZW INTERLEAVE=PIXEL Corner Coordinates: Upper Left (12889228.990,-3724386.063) (115d47' 9.29""E, 31d42'10.76""S) Lower Left (12889228.990,-3749786.049) (115d47' 9.29""E, 31d53'48.88""S) Upper Right (12914628.976,-3724386.063) (116d 0'50.71""E, 31d42'10.76""S) Lower Right (12914628.976,-3749786.049) (116d 0'50.71""E, 31d53'48.88""S) Center (12901928.983,-3737086.056) (115d54' 0.00""E, 31d48' 0.00""S) Band 1 Block=1000x2 Type=Byte, ColorInterp=Red Band 2 Block=1000x2 Type=Byte, ColorInterp=Green Band 3 Block=1000x2 Type=Byte, ColorInterp=Blue }}} If you take coordinate Upper Left as an example: DMS states: 115d47' 9.29""E, 31d42'10.76""S Merc states: 12889228.990,-3724386.063 The actual coordinates of the map are right in DMS but the Merc does not match the DMS after a WGS84 - Merc conversion as below: {{{ DMS 115d47' 9.29""E, 31d42'10.76""S to DD: 115.7859 -31.70299 gdaltransform -s_srs EPSG:4326 -t_srs EPSG:3857 115.7859 -31.70299 12889227.4290409 -3724386.28296906 0 DOES NOT EQUAL 12889228.990 -3724386.063 }}} This is not the same/correct coordinate pair and all the Merc corner coordinates in the gdalinfo are incorrect. I believe mapserver is doing it right because if I project the map to epsg:4283 the corner coordinates are totally right, so I suspect mapserver is outputing it right. [http://www.itbeyond.com.au/images/mapserv.tiff] for reference. ",defect,closed,normal,,default,1.10.1,normal,invalid,,