[gdal-dev] epsg:nnnn results differ from +proj=....

[Matt Wilkie]

dear gdal,

If I assign a projection using an epsg code I get a different result
from gdalinfo than if I assign using the proj4 parameters. Shouldn't the
results be the same?


The proj4 text shown was copied verbatim out of
%fwtools_dir%\proj_lib\epsg for the entry <3578>


----------------------
GDAL 1.5.0b1, FWTools 2.0.2, released 2007/12/05

gdal_translate source.tif test-epsg.tif -a_srs EPSG:3578

gdal_translate source.tif test-proj4.tif -a_srs "+proj=aea
+lat_1=61.66666666666666 +lat_2=68 +lat_0=59 +lon_0=-132.5 +x_0=500000
+y_0=500000 +ellps=GRS80 +datum=NAD83 +units=m +no_defs"

gdalinfo test-epsg.tif
...snip...
Coordinate System is:
PROJCS["NAD83 / Yukon Albers",
     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"]],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]],
     AUTHORITY["EPSG","3578"]]

gdalinfo test-proj4.tif
...snip...
Coordinate System is:
PROJCS["unnamed",
     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["Albers_Conic_Equal_Area"],
     PARAMETER["standard_parallel_1",61.66666666666666],
     PARAMETER["standard_parallel_2",68],
     PARAMETER["latitude_of_center",59],
     PARAMETER["longitude_of_center",-132.5],
     PARAMETER["false_easting",500000],
     PARAMETER["false_northing",500000],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]]]
...snip...
----------------------






-- 
matt wilkie
--------------------------------------------
Geographic Information,
Information Management and Technology,
Yukon Department of Environment
10 Burns Road * Whitehorse, Yukon * Y1A 4Y9
867-667-8133 Tel * 867-393-7003 Fax
http://environmentyukon.gov.yk.ca/geomatics/
--------------------------------------------