I was just sending this e-mail so that it can be searched through the archives. Thanks to Even Rouault for walking me through something that should have been obvious :)
Originally, I was having trouble finding the right parameters for gdalwarp to be able to warp some imagery that I got from Spain. These were in ED50 / UTM zone 31N: rbur...@cuzconix:~/p_bug$ gdalinfo exported_from_original_sid_file.tif Driver: GTiff/GeoTIFF Files: exported_from_original_sid_file.tif Size is 6946, 4800 Coordinate System is: PROJCS["ED50 / UTM zone 31N", GEOGCS["ED50", DATUM["European_Datum_1950", SPHEROID["International 1924",6378388,297.0000000000014, AUTHORITY["EPSG","7022"]], AUTHORITY["EPSG","6230"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4230"]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",0], PARAMETER["central_meridian",3], PARAMETER["scale_factor",0.9996], PARAMETER["false_easting",500000], PARAMETER["false_northing",0], UNIT["metre",1, AUTHORITY["EPSG","9001"]], AUTHORITY["EPSG","23031"]] Origin = (327720.000000000000000,4730783.500000000000000) Pixel Size = (0.500000000000000,-0.500000000000000) Metadata: AREA_OR_POINT=Area Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 327720.000, 4730783.500) ( 0d53'46.94"E, 42d42'34.10"N) Lower Left ( 327720.000, 4728383.500) ( 0d53'49.56"E, 42d41'16.35"N) Upper Right ( 331193.000, 4730783.500) ( 0d56'19.50"E, 42d42'36.88"N) Lower Right ( 331193.000, 4728383.500) ( 0d56'22.08"E, 42d41'19.12"N) Center ( 329456.500, 4729583.500) ( 0d55'4.52"E, 42d41'56.62"N) Band 1 Block=6946x1 Type=Byte, ColorInterp=Red Band 2 Block=6946x1 Type=Byte, ColorInterp=Green Band 3 Block=6946x1 Type=Byte, ColorInterp=Blue In order to get it to work correctly, I had to use the right +towgs84 parameters from http://earth-info.nga.mil/GandG/coordsys/onlinedatum/CountryEuropeTable.html. Although the table showed -84 (+/-5), -107(+/-6), -120 (+/-3), for my own purposes -87, -98, -121 seemed to work best based on my source data. so the command line would be: gdalwarp -s_srs "+proj=utm +zone=31 +ellps=intl +units=m +towgs84=-87,-101,-121 +no_defs" -t_srs EPSG:4326 exported_from_original_sid_file.tif testout.tif Hope this helps someone else, - Ragi
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