[GRASS-user] importing HDF sea ice grid with unusual projection

[Markus Neteler]

On Thu, Nov 5, 2009 at 7:27 PM, Seb <spluque at gmail.com> wrote:
> Hi,
>
> I'm in the process of importing sea ice concentration data from:
>
> ftp://ftp-projects.zmaw.de/seaice/AMSR-E_ASI_IceConc
>
> I have chosen to use their HDF product because their Geotiff uses a
> WGS84 datum that results in up to 500 m error at the borders, according
> to their info files at the root of each subdirectory.
>
> The grids are not georeferenced, but they use the same grid that NSIDC
> does with the specifications given here:
>
> http://nsidc.org/data/docs/daac/nsidc0002_ssmi_seaice.gd.html
>
> Fortunately, there's an EPSG code (3411, for the northern hemisphere)
> for that projection.
>
> gdalinfo on the HDF file:
>
> ---<--------------------cut here---------------start------------------->---
> $ gdalinfo asi-n6250-20020619-v5i.hdf
> Driver: HDF4Image/HDF4 Dataset
> Files: asi-n6250-20020619-v5i.hdf
> Size is 1216, 1792
> Coordinate System is `'
> Metadata:
>  valid_range=0, 1
>  long_name=ASI Ice Concentration, 20020619, res: 6.25000, AMSR-E, ASI Version: 5.5i, missing data interpolated.
> Corner Coordinates:
> Upper Left  (    0.0,    0.0)
> Lower Left  (    0.0, 1792.0)
> Upper Right ( 1216.0,    0.0)
> Lower Right ( 1216.0, 1792.0)
> Center      (  608.0,  896.0)
> Band 1 Block=1216x82 Type=Float32, ColorInterp=Gray
> ---<--------------------cut here---------------end--------------------->---
>
> Converting to GTiff for importing into GRASS, using the EPSG code and
> bounds in the NSIDC's info:
>
> ---<--------------------cut here---------------start------------------->---
> $ gdal_translate -of GTiff -a_srs EPSG:3411 -a_ullr -3800000 5600000 3800000 -5600000 asi-n6250-20020619-v5i.hdf asi-n6250-20020619-v5i.tif
> Warning 6: A dataset opened by GDALOpenShared should have the same filename (asi-n6250-20020619-v5i.hdf) and description (HDF4_SDS:UNKNOWN:"asi-n6250-20020619-v5i.hdf":0)
> Input file size is 1216, 1792
> 0...10...20...30...40...50...60...70...80...90...100 - done.
>
> $ gdalinfo asi-n6250-20020619-v5i.tif
> Driver: GTiff/GeoTIFF
> Files: asi-n6250-20020619-v5i.tif
> Size is 1216, 1792
> Coordinate System is:
> PROJCS["NSIDC Sea Ice Polar Stereographic North",
>    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","3411"]]
> Origin = (-3800000.000000000000000,5600000.000000000000000)
> Pixel Size = (6250.000000000000000,-6250.000000000000000)
> Metadata:
>  AREA_OR_POINT=Area
>  valid_range=0, 1
>  long_name=ASI Ice Concentration, 20020619, res: 6.25000, AMSR-E, ASI Version: 5.5i, missing data interpolated.
> Image Structure Metadata:
>  INTERLEAVE=BAND
> Corner Coordinates:
> Upper Left  (-3800000.000, 5600000.000)
> Lower Left  (-3800000.000,-5600000.000)
> Upper Right ( 3800000.000, 5600000.000)
> Lower Right ( 3800000.000,-5600000.000)
> Center      (   0.0000000,   0.0000000)
> Band 1 Block=1216x1 Type=Float32, ColorInterp=Gray
> ---<--------------------cut here---------------end--------------------->---
>
> So far so good, but when importing into a GRASS location:
>
> ---<--------------------cut here---------------start------------------->---
> r.in.gdal in=/home/sluque/tmp/asi-n6250-20020619-v5i.tif out=test location=Test
> WARNING: No projection name! Projection parameters likely to be
>         meaningless.
> WARNING: Datum <Not_specified_based_on_Hughes_1980_ellipsoid> not
>         recognised by GRASS and no parameters found
> Location <Test> created
>  100%
> r.in.gdal complete. Raster map <test> created.
> ---<--------------------cut here---------------end--------------------->---
>
> What is missing here?  I've also tried using the proj4 strings offered
> for that EPSG, but the results are the same.  Any tips would be appreciated.


I don't have much to add but also had problems to import some NSIDC maps.
Perhaps this is relevant?
http://trac.osgeo.org/gdal/ticket/2584

In general it is more a question for the GDAL folks since GRASS uses
GDAL for import.

Markus