[Gdal-dev] use of .prj file

[Doug_Newcomb at fws.gov]

Hi folks,
      Using FWtools1.0.0b2  on windows  - gdal_translate with the -a_srs
option with the following .prj file to define the projection in converting
a tiff to an ecw file:

PROJCS["NAD_1983_UTM_Zone_18N",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-75.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]

Output from gdalinfo  *.ecw gives the following projection information

Driver: ECW/ERMapper Compressed Wavelets
Size is 10000, 10000
Coordinate System is:
PROJCS["UTM Zone 18, Northern Hemisphere",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9108"]],
        AXIS["Lat",NORTH],
        AXIS["Long",EAST],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",-75],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["Meter",1]]

gdal_translate appears to be missing the NAD83 information in the .prj
file.  Is this a known issue?  It is also occuring with gdal-cvs-2006.03.01
and proj 4.4.9 both  compiled from sources ( with the NAD conversion files)
on linux .



Doug Newcomb
USFWS
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
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