Hi Jean-Claude, many thanks for your answer.
As you can see I did not specifiy the ellipsoid parameter: gdalwarp -s_srs EPSG:27700 -t_srs EPSG:4326 input_geotiff_in_BNG.tiff output_geotiff.tiff the gdal error message was: ERROR 6: Failed to initialize PROJ.4 with `+proj=tmerc +lat_0=49 +lon_0=-2 +k=0. 9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36 +units=m +no_defs'. unknown elliptical parameter name Is that a bug in GDAL? Many thanks ----- Original Message ----- From: [email protected] Date: 23.03.2010 19:06:33 Subject: Re: [gdal-dev] Problem with +ellps=airy which is used for BNG > Andreas Joisten a écrit : > > Hi all, > > > > The BNG (British Natial Grid) based on the airy Ellipsoid but GDAL did not > > know this parameter. > > > > > > +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 > > +ellps=airy +datum=OSGB36 +units=m +no_defs > > > > Probably, gdal does not know this parameter: +ellps=airy > > Hello, > > You don't need to specify the ellipsoid, because it is already contained > in the datum definition : > > proj -v +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 > +y_0=-100000 +datum=OSGB36 +units=m +no_defs > #Transverse Mercator > # Cyl, Sph&Ell > # +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 > # +datum=OSGB36 +units=m +no_defs +ellps=airy > # +towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894 > > Jean-Claude > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
