[gdal-dev] Create Coordinate Transformation always returns NULL

[Clay, Bruce]

Mystery solved - at least the initial part - My GDAL / OGR build does
not have Proj4 included as a static library and I did not have the DLL
in the execution path.

 

Is there a way to query OGR to get an error message or code that
explains why an operation fails?

 

Bruce

________________________________

From: gdal-dev-bounces at lists.osgeo.org
[mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Clay, Bruce
Sent: Wednesday, March 12, 2008 5:33 PM
To: gdal-dev at lists.osgeo.org
Subject: [gdal-dev] Create Coordinate Transformation always returns NULL

 

I am trying to create a transformation from WGS 84 to a projected
system.  I have tried several but create transform always returns NULL.

The code I am using is essentially the reverse sequence as shown in the
OSR tutorial.  That is that the example went from a projected frame to a
geodetic frame.

The returned status for each of the steps is 0 so it looks like
everything should work and this type of transform is fairly common so I
would think it should be supported by proj4 but I don't see anything in
the proj4 docs that describe what types are supported.

 

Any ideas would be greatly appreciated

 

Bruce

 

////////////////////////////////////////////////////////////////////////
///////

OGRCoordinateTransformation *GdalWrapper::CreateWellKnownTransformation(

                  const char *srcWngcsSrs, const char *destWngcsSrs)

{

      int status = -1;

      OGRErr ogrStatus;

      OGRCoordinateTransformation *coordTransPtr = NULL;

 

      OGRSpatialReference srcSpatialRef;

      OGRSpatialReference destSpatialRef;

 

      ogrStatus = srcSpatialRef.SetWellKnownGeogCS("WGS84");

 

      if (ogrStatus == 0)

      {

            ogrStatus = destSpatialRef.SetProjCS("UTM 17 / WGS84" );

            ogrStatus = destSpatialRef.SetWellKnownGeogCS( "WGS84" );

            ogrStatus = destSpatialRef.SetUTM( 17, TRUE );

 

            if (ogrStatus == 0)

            {

                  coordTransPtr = OGRCreateCoordinateTransformation(

                              &srcSpatialRef, &destSpatialRef);

            }

      }

      return(coordTransPtr);

}

 



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