[gdal-dev] ERROR 6: Failed to initialize PROJ.4 -- convert from BNG to WGS84; using gdalwarp

[Andreas Joisten]

Hi all,

I want to use gdalwarp to convert a GeoTiff file in BNG (British National Grid) to WGS84, but I got the following error:

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
'.

The input file in BNG looks like:

Size is 2365, 2366
Coordinate System is:
PROJCS["unnamed",
    GEOGCS["OSGB 1936",
        DATUM["OSGB_1936",
            SPHEROID["Airy 1830",6377563.396,299.3249646000044,
                AUTHORITY["EPSG","7001"]],
            AUTHORITY["EPSG","6277"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4277"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",49],
    PARAMETER["central_meridian",-2],
    PARAMETER["scale_factor",0.9996012717],
    PARAMETER["false_easting",400000],
    PARAMETER["false_northing",-100000],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]
Origin = (546999.336021105410000,263500.317128534600000)
Pixel Size = (0.634719746381245,-0.634719746381245)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  546999.336,  263500.317)
Lower Left  (  546999.336,  261998.570)
Upper Right (  548500.448,  263500.317)
Lower Right (  548500.448,  261998.570)
Center      (  547749.892,  262749.444)
Band 1 Block=2365x3 Type=Byte, ColorInterp=Palette


This is the command to convert into WGS84:

gdalwarp -s_srs "+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" -t_srs "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs" geo_BNG_proj4.tif  geo_wgs84_13.tif


Which data is required to initialize PROJ.4 correct?


Many thanks for your help.