[Gdal-dev] OGR Spatial Questions

[pvg]

Hi Frank,

I've been having some trouble trying to post to the gdal news group so 
I'm sending this email directly to you. Maybe it will post this time??

I've just begun my long intended projected of replacing ("gutting") my 
attempts at projection support with your OGR. What I've done is compile 
a small DLL with the core ORG spatial routines. I'm testing by reading 
Geotiffs (UTM and Albers) and trying to get Lat/Long screen coordinates. 
Running into some trouble. First I tested with some of your examples:

    OGRSpatialReference    oUTM, *poLatLong;
    OGRCoordinateTransformation *poTransform;

    oUTM.SetProjCS("UTM 17 / WGS84");
    oUTM.SetWellKnownGeogCS( "WGS84" );
    oUTM.SetUTM( 17 );

    poLatLong = oUTM.CloneGeogCS();
    poTransform = OGRCreateCoordinateTransformation( &oUTM, poLatLong );

Works fine. Then I load a geotiff and try the following:

    char *pszProjection = GTIFGetOGISDefn(gtif, &defn );
    // string looks like it should

    OGRSpatialReference oSRS;
    OGRErr i = oSRS.SetProjection( pszProjection );

To this point seem ok.

    OGRSpatialReference    *poLatLong2;
    poLatLong2 = oSRS.CloneGeogCS();

NADA, return NULL. Am I missing a key step in setting up projections 
form geotiffs? Could this be related to proj.dll (I using the 
precompiled binary from the proj4 site)? Before I start digging I'm 
hoping there is an easy solution.

This is my first go at your code and using the proj4 dll.

Thanks,
Peter