[gdal-dev] gdalinfo, map unit DD and epsg:9108

Frank Warmerdam warmerdam at pobox.com
Fri Nov 19 11:56:53 EST 2010

yrrman yrrman wrote:
> the Global Landcover set GLC2000 is available in grid format from [0].
> Associated with it is the .hdr file with the projection description
> [2].
> Apparently the map units are in decimal degree.
> When I ask gdalinfo, I get the WKT description of the SRS, see [3]
> Everything's fine with this, I only came across the UNIT-Field
>  UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9108"]],
> where the unit is degree, defined according to epsg:9108. When you
> look up epsg:9108 in the epsg registry [1] you get as Unit of Measure:
> Code: EPSG::9108 - Name: degree minute second hemisphere (i.e. not
> decimal degree)
> Shouldn't this rather be epsg:9102 then?
> Code: EPSG::9102 Name: degree, 1 degree: 0.017453292519943278 radian


For WKT representations we deliberately use decimal degrees instead of
DMS format for convenient processing.  So the result isn't quite exactly
according to EPSG but the difference is deliberate and in my opinion
is important for interoperability.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

More information about the gdal-dev mailing list