[Gdal-dev] decimal degrees coordinates don't match degrees minutes seconds coordinates

[Ed McNierney]

John -

Where are you seeing decimal degrees?  The first corner coordinate is:

Upper Left  (  742500.000, 4275000.000) ( 90d12' 56.63"W, 38d35'25.40"N)

Which is telling you the corner coordinates in the image¹s native projection
(UTM Zone 15N) in the first pair (742500.000, 4275000.000) and then giving
you that point in degrees/minutes/seconds.  There are no decimal degrees
displayed.

A rectangle in UTM space/coordinates is not a rectangle in lat/lon
coordinates, so the upper left latitude and the upper right latitude should
not be expected to be the same.

     - Ed

-- 
Ed McNierney
President and Chief Mapmaker
Maps a la carte, Inc. / TopoZone.com
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: (978) 251-4242
Fax: (978) 251-1396
ed at topozone.com


From: John Mitchell <mitchelljj98 at gmail.com>
Date: Tue, 30 Jan 2007 15:14:36 -0500
To: Gdal-Dev <gdal-dev at lists.maptools.org>
Cc: <mitchelljj98 at gmail.com>
Subject: [Gdal-dev] decimal degrees coordinates don't match degrees minutes
seconds coordinates

Within gdalinfo I noticed that the decimal degrees corner coordinates are
rectangular but to the right the degrees minutes seconds corner coordinates
are not rectangular.

Below is a gdalinfo dump:

Driver: GTiff/GeoTIFF
Size is 10000, 10000
Coordinate System is:
PROJCS["NAD83 / UTM zone 15N",
    GEOGCS["NAD83",
        DATUM["North_American_Datum_1983",
            SPHEROID["GRS 1980",6378137, 298.2572221010002,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","6269"]],
        PRIMEM["Greenwich",0],
        UNIT["degree", 0.0174532925199433],
        AUTHORITY["EPSG","4269"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",-93],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","26915"]]
Origin = (742500.000000000000000,4275000.000000000000000)
Pixel Size = (0.150000000000000,-0.150000000000000)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_SOFTWARE=Adobe Photoshop CS Windows
  TIFFTAG_DATETIME=2005:12:29 11:49:37
  TIFFTAG_XRESOLUTION=72
  TIFFTAG_YRESOLUTION=72
  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
Corner Coordinates:
Upper Left  (  742500.000, 4275000.000) ( 90d12' 56.63"W, 38d35'25.40"N)
Lower Left  (  742500.000, 4273500.000) ( 90d12'58.51"W, 38d34'36.79"N)
Upper Right (  744000.000, 4275000.000) ( 90d11'54.70"W, 38d35'23.92"N)
Lower Right (  744000.000, 4273500.000) ( 90d11'56.59"W, 38d34'35.31"N)
Center      (  743250.000, 4274250.000) ( 90d12'26.61"W, 38d35'0.36"N)
Band 1 Block=10000x5 Type=Byte, ColorInterp=Red
Band 2 Block=10000x5 Type=Byte, ColorInterp=Green
Band 3 Block=10000x5 Type=Byte, ColorInterp=Blue


-- 
John J. Mitchell

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