[gdal-dev] Export HDF-EOS to GeoTIFF

[Frank Warmerdam]

Denis Rykov wrote:
> I'm trying export raster from HDF-EOS to GeoTIFF. At result I have 
> GeoTiff with 143 numbers of GCP.
> There are some thousands GCP at HDF-EOS geolocation SDS. Is OGR drivers 
> support only 143 GCP?

Denis,

Normally the HDF4 driver takes only a subset of GCPs to keep the number
managable.  The logic looks like:

/* -------------------------------------------------------------------- */
/*      Determine whether to use no, partial or full GCPs.              */
/* -------------------------------------------------------------------- */
     const char *pszGEOL_AS_GCPS = CPLGetConfigOption( "GEOL_AS_GCPS",
                                                       "PARTIAL" );
     int iGCPStepX, iGCPStepY;

     if( EQUAL(pszGEOL_AS_GCPS,"NONE") )
     {
         iGCPStepX = iGCPStepY = 0;
     }
     else if( EQUAL(pszGEOL_AS_GCPS,"FULL") )
     {
         iGCPStepX = iGCPStepY = 1;
     }
     else
     {
         // aim for 10x10 grid or so.
         iGCPStepX = MAX(1,((nXPoints-1) / 11));
         iGCPStepY = MAX(1,((nYPoints-1) / 11));
     }

So if you want them all you can set the configuration variable
GEOL_AS_GCPS to FULL either in the environment or as a commandline
switch ("--config GEOL_AS_GCPS FULL").

Best regards,
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