[gdal-dev] Gamma parameter not set in proj4 string for RSO projections

[Hilmy Hashim]

Sorry to bring this up again. I've been looking for why epsg_tr.py -proj4 is
not including the +gamma (RectifiedToSkew angle) parameter for the
+proj=omerc projection as used in EPSG:3168, EPSG:3375, etc. It seems that
it is not set in
https://svn.osgeo.org/fdo/trunk/Thirdparty/gdal/ogr/ogr_srs_proj4.cpp:

else if( EQUAL(pszProj,"omerc") )

    {
        SetHOM( OSR_GDV( papszNV, "lat_0", 0.0 ),
                OSR_GDV( papszNV, "lonc", 0.0 ),
                OSR_GDV( papszNV, "alpha", 0.0 ),
                0.0, /* ??? */
                OSR_GDV( papszNV, "k", 1.0 ),
                OSR_GDV( papszNV, "x_0", 0.0 ),
                OSR_GDV( papszNV, "y_0", 0.0 ) );
    }

...


        else
        {
            sprintf( szProj4+strlen(szProj4),
                     "+proj=omerc +lat_0=%.16g +lonc=%.16g +alpha=%.16g"
                     " +k=%.16g +x_0=%.16g +y_0=%.16g ",
                     GetNormProjParm(SRS_PP_LATITUDE_OF_ORIGIN,0.0),
                     GetNormProjParm(SRS_PP_CENTRAL_MERIDIAN,0.0),
                     GetNormProjParm(SRS_PP_AZIMUTH,0.0),
                     GetNormProjParm(SRS_PP_SCALE_FACTOR,1.0),
                     GetNormProjParm(SRS_PP_FALSE_EASTING,0.0),
                     GetNormProjParm(SRS_PP_FALSE_NORTHING,0.0) );
        }

There seems to be some uncertainty about this parameter. How can this be
resolved and how can I help?

Thanks.

*Hilmy*
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