Thanks Frank/Hermann for your responses. However, something odd seems
to be going on here. I feel like I'm missing something on how GDAL
handles coordinate system information.
Using the same input data set, and converting to different formats, the
description of the output coordinate systems are different. Is this
expected? Here are the gdal_translate commands and their respective
output files gdalinfo descriptions below.
[1] gdal_translate -a_srs "+proj=stere +lat_0=-90 +lat_ts=-70 +lon_0=0
+k=1 +x_0=0 +y_0=0 +a=6378273 +b=6356889.449 +units=m +no_defs" -of
GTiff nt_200712_f13_v01_s.bsq nsidc_test.tif
[2] gdal_translate -a_srs "+proj=stere +lat_0=-90 +lat_ts=-70 +lon_0=0
+k=1 +x_0=0 +y_0=0 +a=6378273 +b=6356889.449 +units=m +no_defs" -of HFA
nt_200712_f13_v01_s.bsq nsidc_test.img
[3] gdal_translate -a_srs "+proj=stere +lat_0=-90 +lat_ts=-70 +lon_0=0
+k=1 +x_0=0 +y_0=0 +a=6378273 +b=6356889.449 +units=m +no_defs" -of
HDF4Image nt_200712_f13_v01_s.bsq nsidc_test.hdf
[4] gdal_translate -a_srs EPSG:3412 -of GTiff nt_200712_f13_v01_s.bsq
nsidc_test_epsg.tif
[5] gdal_translate -a_srs EPSG:3412 -of HFA nt_200712_f13_v01_s.bsq
nsidc_test_epsg.img
Fortunately, I can display these images fine. They overlay nicely in
QGIS with some vector data I have. However, the problem occurs when
projecting to EPSG:4326 (or similar) coordinate system; the output files
are incorrect/missing data. (It displays data from roughly lat -39.25
only down to roughly -54.75 when data exists all the way down to -90.)
One possible cause could be that gdalinfo reports (for all of these
datasets) latitude_of_origin as -70. From
http://nsidc.org/data/atlas/epsg_3412.html, the latitude of origin
should be -90 and the latitude of standard parallel should be -70. Or
the problem could be somewhere in gdalwarp, or specifically with the
Hughes 1980 ellipsoid. I have no idea. Thanks.
- John
[1] Driver: GTiff/GeoTIFF
Files: nsidc_test.tif
Size is 316, 332
Coordinate System is:
PROJCS["unnamed",
GEOGCS["unnamed ellipse",
DATUM["unknown",
SPHEROID["unnamed",6378273,298.279411123061]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],
PROJECTION["Polar_Stereographic"],
PARAMETER["latitude_of_origin",-70],
PARAMETER["central_meridian",0],
PARAMETER["scale_factor",1],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]]]
Origin = (-3950000.000000000000000,4350000.000000000000000)
Pixel Size = (25000.000000000000000,-25000.000000000000000)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
INTERLEAVE=BAND
Corner Coordinates:
Upper Left (-3950000.000, 4350000.000) ( 42d14'27.21"W, 39d13'51.20"S)
Lower Left (-3950000.000,-3950000.000) (135d 0'0.00"W, 41d26'49.04"S)
Upper Right ( 3950000.000, 4350000.000) ( 42d14'27.21"E, 39d13'51.20"S)
Lower Right ( 3950000.000,-3950000.000) (135d 0'0.00"E, 41d26'49.04"S)
Center ( 0.000, 200000.000) ( 0d 0'0.01"E, 88d 9'14.17"S)
Band 1 Block=316x25 Type=Byte, ColorInterp=Gray
[2] Driver: HFA/Erdas Imagine Images (.img)
Files: nsidc_test.img
Size is 316, 332
Coordinate System is:
PROJCS["Stereographic_South_Pole",
GEOGCS["GCS_unnamed ellipse",
DATUM["unknown",
SPHEROID["Unknown",6378273,298.279411123061]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Polar_Stereographic"],
PARAMETER["latitude_of_origin",-70],
PARAMETER["central_meridian",0],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["Meter",1]]
Origin = (-3950000.000000000000000,4350000.000000000000000)
Pixel Size = (25000.000000000000000,-25000.000000000000000)
Corner Coordinates:
Upper Left (-3950000.000, 4350000.000) ( 42d14'27.21"W, 39d13'51.20"S)
Lower Left (-3950000.000,-3950000.000) (135d 0'0.00"W, 41d26'49.04"S)
Upper Right ( 3950000.000, 4350000.000) ( 42d14'27.21"E, 39d13'51.20"S)
Lower Right ( 3950000.000,-3950000.000) (135d 0'0.00"E, 41d26'49.04"S)
Center ( 0.000, 200000.000) ( 0d 0'0.01"E, 88d 9'14.17"S)
Band 1 Block=64x64 Type=Byte, ColorInterp=Undefined
Metadata:
LAYER_TYPE=athematic
[3] Driver: HDF4Image/HDF4 Dataset
Files: nsidc_test.hdf
Size is 316, 332
Coordinate System is:
PROJCS["unnamed",
GEOGCS["unnamed ellipse",
DATUM["unknown",
SPHEROID["unnamed",6378273,298.279411123061]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],
PROJECTION["Polar_Stereographic"],
PARAMETER["latitude_of_origin",-70],
PARAMETER["central_meridian",0],
PARAMETER["scale_factor",1],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["Meter",1]]
Origin = (-3950000.000000000000000,4350000.000000000000000)
Pixel Size = (25000.000000000000000,-25000.000000000000000)
Metadata:
Signature=Created with GDAL (http://www.remotesensing.org/gdal/)
TransformationMatrix=-3950000.000000, 25000.000000, 0.000000,
4350000.000000, 0.000000, -25000.000000
Projection=PROJCS["unnamed",GEOGCS["unnamed
ellipse",DATUM["unknown",SPHEROID["unnamed",6378273,298.279411123061]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]],PROJECTION["Polar_Stereographic"],PARAMETER["latitude_of_origin",-70],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["Meter",1]]
Corner Coordinates:
Upper Left (-3950000.000, 4350000.000) ( 42d14'27.21"W, 39d13'51.20"S)
Lower Left (-3950000.000,-3950000.000) (135d 0'0.00"W, 41d26'49.04"S)
Upper Right ( 3950000.000, 4350000.000) ( 42d14'27.21"E, 39d13'51.20"S)
Lower Right ( 3950000.000,-3950000.000) (135d 0'0.00"E, 41d26'49.04"S)
Center ( 0.000, 200000.000) ( 0d 0'0.01"E, 88d 9'14.17"S)
Band 1 Block=316x316 Type=Byte, ColorInterp=Gray
[4] Driver: GTiff/GeoTIFF
Files: nsidc_test_epsg.tif
Size is 316, 332
Coordinate System is:
PROJCS["NSIDC Sea Ice Polar Stereographic South",
GEOGCS["Unspecified datum based upon the Hughes 1980 ellipsoid",
DATUM["Not_specified_based_on_Hughes_1980_ellipsoid",
SPHEROID["Hughes 1980",6378273,298.279411123061,
AUTHORITY["EPSG","7058"]],
AUTHORITY["EPSG","6054"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4054"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AUTHORITY["EPSG","3412"]]
Origin = (-3950000.000000000000000,4350000.000000000000000)
Pixel Size = (25000.000000000000000,-25000.000000000000000)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
INTERLEAVE=BAND
Corner Coordinates:
Upper Left (-3950000.000, 4350000.000)
Lower Left (-3950000.000,-3950000.000)
Upper Right ( 3950000.000, 4350000.000)
Lower Right ( 3950000.000,-3950000.000)
Center ( 0.000, 200000.000)
Band 1 Block=316x25 Type=Byte, ColorInterp=Gray
[5] Driver: HFA/Erdas Imagine Images (.img)
Files: nsidc_test_epsg.img
Size is 316, 332
Coordinate System is:
PROJCS["NSIDC_Sea_Ice_Polar_Stereographic_South",
GEOGCS["GCS_Unspecified datum based upon the Hughes 1980 ellipsoid",
DATUM["Hungarian_Datum_1909",
SPHEROID["Hughes_1980",6378273,298.279411123061]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Polar_Stereographic"],
PARAMETER["latitude_of_origin",-70],
PARAMETER["central_meridian",0],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["Meter",1]]
Origin = (-3950000.000000000000000,4350000.000000000000000)
Pixel Size = (25000.000000000000000,-25000.000000000000000)
Corner Coordinates:
Upper Left (-3950000.000, 4350000.000) ( 42d14'27.21"W, 39d13'51.20"S)
Lower Left (-3950000.000,-3950000.000) (135d 0'0.00"W, 41d26'49.04"S)
Upper Right ( 3950000.000, 4350000.000) ( 42d14'27.21"E, 39d13'51.20"S)
Lower Right ( 3950000.000,-3950000.000) (135d 0'0.00"E, 41d26'49.04"S)
Center ( 0.000, 200000.000) ( 0d 0'0.01"E, 88d 9'14.17"S)
Band 1 Block=64x64 Type=Byte, ColorInterp=Undefined
Metadata:
LAYER_TYPE=athematic
Frank Warmerdam wrote:
Hermann Peifer wrote:
John Callahan wrote:
Thanks for responding Hermann. Yes, I tried using -s_srs EPSG:3412
as well as the full PROJ4 string with the same result. When
specifying -s_srs, does gdalwarp ignore (override) the project
information in the hdr file?
Hmm. AFAIK: gdal_translate -a_srs does override the file's projection
information. I have a random.tif in LAEA projection (EPSG:3035), so I
tried the following with gdal 1.6.2:
gdal_translate random.tif out1.tif -a_srs EPSG:3412 # this results
in [1]
gdal_translate random.tif out2.tif -a_srs "+proj=stere +lat_0=-90
+lat_ts=-70 +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378273 +b=6356889.449
+units=m +no_defs" # this gives [2]
To me as an innocent GDAL user, this behaviour looks similar to
http://trac.osgeo.org/gdal/ticket/3016. I might be wrong, though, in
particular as you wrote that using the PROJ.4 string didn't help (and
your source file isn't a GeoTIFF in the first place).
Hermann,
I have confirmed this problem and filed it as:
http://trac.osgeo.org/gdal/ticket/3220
It is presumably a problem with translation of a specific projection
method,
possibly in libgeotiff itself.
Best regards,
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