[Gdal-dev] Use of gdalwarp/translate utility

[Doug Nebert]

I have a series of images that are 2000x2000 pixels centered on the 
polar regions in a EPSG:3413 projection, though Proj.4/GDAL don't seem 
to know about it yet. I'd like to take the GIFs and embed the 
projection information in the TIFF header so that they may be 
used/interpreted in applications such as transformation to other 
projections.

I've been trying gdal_translate to do this assignment, and gdalinfo 
seems to show some things being set. And yet, I am getting pixels equal 
to units of measure, instead of meters.

The details of this unusual projection:

Based on Polar Stereographic (variant B) method
Base CRS and ellipsoid are WGS84
Latitude of standard parallel: 70N (where the plane intersects)
Longitude of origin: 45W (Greenland is centered)

so I figured I could assign these by hand:

gdal_translate -a_srs "+proj=stere +datum=wgs84 +lat_ts=70.0 +lat_0=90 
+lon_0=-45" -of GTiff input1.gif quickscat1.tif

But my reported coordinates when panning around the image are in pixel 
coordinates, not in meters.

What am I missing in the assignment?

gdalinfo says:

Driver: GTiff/GeoTIFF
Size is 1530, 1530
Coordinate System is:
PROJCS["unnamed",
     GEOGCS["WGS 84",
         DATUM["WGS_1984",
             SPHEROID["WGS 84",6378137,298.2572235630016,
                 AUTHORITY["EPSG","7030"]],
             AUTHORITY["EPSG","6326"]],
         PRIMEM["Greenwich",0],
         UNIT["degree",0.0174532925199433],
         AUTHORITY["EPSG","4326"]],
     PROJECTION["Polar_Stereographic"],
     PARAMETER["latitude_of_origin",70],
     PARAMETER["central_meridian",-45],
     PARAMETER["scale_factor",1],
     PARAMETER["false_easting",0],
     PARAMETER["false_northing",0],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]]]
Metadata:
   AREA_OR_POINT=Area
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0, 1530.0)
Upper Right ( 1530.0,    0.0)
Lower Right ( 1530.0, 1530.0)
Center      (  765.0,  765.0)



-- 
Douglas D. Nebert
Geospatial Data Clearinghouse Coordinator, Information Architect
FGDC/GSDI Secretariat   Phone: +1 703 648 4151  Fax: +1 703 648-5755