[gdal-dev] (no subject)

[Sjur Kolberg]

Hello, GDAL list;
 
Can anyone suggest what prevents the following GDALSuggestedWarpOutput 
from calculating an approximate geotransform? The resulting suggested 
GeoTransform is just a copy of the original GeoTransform.
 
Version is GDAL 1.6.0beta1 under Windows XP, I use Visual Studio 2005, 
this is a MFC application. poDataset is a 9900 band GRIB 1 data set 
from ECMWF. It appears to be read in OK, I can extract 
plausible metadata both from the dataset and from each band. 
 
   SourceWKT is (CString)
GEOGCS["Coordinate System imported from GRIB file",DATUM["unknown",
SPHEROID["Sphere",6367470,0]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
   SourceWKT is from poDataset->GetProjectionRef()
 
   TargetWKT is (CString)
PROJCS["UTM 32 North (WGS84)",GEOGCS["WGS 84",DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],
TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",
0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9108"]],AXIS["Lat",NORTH],AXIS["Long",EAST],
AUTHORITY["EPSG","4326"]],PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",9],
PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],UNIT["Meter",1]]
   TargetWKT is from 
ogrspatref.SetProjCS(msg);                        // CString msg is just a name
ogrspatref.SetWellKnownGeogCS( "WGS84" );
if (ogrspatref.SetUTM( zone, i ) != OGRERR_NONE)  // zone==32, i==1 for northern hem.
 
 
And the code goes:


void *hTransformArg = GDALCreateGenImgProjTransformer( 
poDataset, sourceWKT, NULL, targetWKT, FALSE, 0, 1 );

CPLAssert( hTransformArg != NULL );

if (GDALSuggestedWarpOutput(pSrcDS, GDALGenImgProjTransform, 
hTransformArg, SugGeoTransform, &nPixels, &nLines )  != CE_None )

throw new GeneralExcpt("GDALSuggestedWarpOutput failed");




No exception is thown or other error, so everything 
seems OK, but the resulting SugGeoTransform is:

  [0] 4.0000000000000000 double
  [1] 0.25000000000000000 double
  [2] 0.00000000000000000 double
  [3] 65.000000000000000 double
  [4] 0.00000000000000000 double
  [5] -0.25000000000000000 double
and nPixels, nLines are 33, 45 
This happens to be exactly the GeoTransform of poDataSet, in degrees.
 
 
I guess I'm missing something obvious, but I've spent some evenings now.
 
Thanks for any help.
 
Sjur K :-)