[gdal-dev] gdal to define projection, EPSG:3412

John Callahan john.callahan at UDel.Edu
Tue Nov 10 15:00:58 EST 2009

Is it possible to define/set a coordinate system using GDAL?   I 
downloaded some data (from NSIDC) I know is in EPSG:3412.  

The data is in bsq format, therefore requires a hdr file that I've been 
piecing together manually.  The hdr file has a "projection info" line 
that defines the projection parameters.   Here is the hdr file I've been 
using, unsuccessfully:

description = {
  File Imported into ENVI.}
samples = 316
lines   = 332
bands   = 1
header offset = 300
file type = ENVI Standard
data type = 1
interleave = bsq
sensor type = Unknown
byte order = 0
map info = {NSIDC Sea Ice Polar Stereographic South, 1.0000, 1.0000, 
-3950000.0000, 4350000.0000, 2.5000000000e+004, 2.5000000000e+004, 
Hughes 1980, units=Meters}
projection info = {31, 6378273.0, 6356889.4, -70.000000, 0.000000, 0.0, 
0.0, Hughes1980, NSIDC Sea Ice Polar Stereographic South, units=Meters}
wavelength units = Unknown
pixel size = {2.50000000e+004, 2.50000000e+004, units=Meters}

The data displays properly with other vector data in EPSG:3412, say in 
QGIS.  To me, this simply means the "map info" line of correct.  
However, when I try to project the data (gdal_translate, gdalwarp), the 
output is nonsense (nearly all null or nodata).  I believe my 
"projection info" line is wrong, and may have something to do with 
denoting the lat of origin as -90 and standard parallel as -70.   Thanks 
for any help.

- John

John Callahan, Geospatial Application Developer
Delaware Geological Survey, University of Delaware
URL: http://www.dgs.udel.edu

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