It looks like arcgis does not support Mercator_1SP in geotiff files. It just ignores the scale factor and uses 1.0. Which means in GDAL and libgeotiff as they are now, there is no way to export Mercator projections that don't have a scale of 1.0 to arcgis.
ArcGIS does support Mercator_2SP, but instead of placing the latitude of true scale in ProjStdParallel1GeoKey, it uses ProjNatOriginLatGeoKey. Which seems to be plainly wrong, yet that's what it does. I wonder if ESRI used libgeotiff? With unpatched libgeotiff, the only way to get a latitude from a Mercator geotiff it to use one of the origin latitude GeoKeys. It's not correct, but it does allow one to stick the number in the file and get it back out without having to modify or understand any libgeotiff code. It's possible that ArcGIS supports getting the latitude of true scale from ProjStdParallel1GeoKey, even it it doesn't store it there. Antii, could you test this file with ArcGIS? https://drive.google.com/file/d/0BybuTedE9CLxak9iakZRTC00cHM/edit?usp=sharing Pick file->download to get the geotiff file. It should have projection information like this: PROJECTION["Mercator_2SP"], PARAMETER["standard_parallel_1",47.667], PARAMETER["central_meridian",0], PARAMETER["false_easting",0], PARAMETER["false_northing",0], UNIT["metre",1, AUTHORITY["EPSG","9001"]]] Origin = (-9278434.534151820465922,4143530.208984711207449) Pixel Size = (240.003786961970206,-240.003786961970206) Corner Coordinates: Upper Left (-9278434.534, 4143530.209) (123d32'26.22"W, 48d23'56.59"N) Lower Left (-9278434.534, 3984167.694) (123d32'26.22"W, 46d57'58.64"N) Upper Right (-9165872.758, 4143530.209) (122d 2'30.76"W, 48d23'56.59"N) Lower Right (-9165872.758, 3984167.694) (122d 2'30.76"W, 46d57'58.64"N) Center (-9222153.646, 4063848.952) (122d47'28.49"W, 47d41'15.43"N) _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev