[gdal-dev] OSGB36 to WGS84 transformation

[Hermann Peifer]

The lower left corner coordinates of the SD square are:
300 000 metres East
400 000 metres North

So your test coordinate is at (Easting Northing): 380150 402109

echo "380150 402109" | gdaltransform -s_srs EPSG:27700 -t_srs EPSG:4326
-2.30083027968938 53.5152719980087 48.8662291513756

Please note that behind the scenes, these datum shift parameters are 
applied: +towgs84=375,-111,431,0,0,0,0 (which might be what you want .. 
or not).

Hermann


On 2013-01-08 21:17, Johnny wrote:
> Hi,
>
> I am trying to convert OSGB grid references to WGS84, but do not succeed
> and don't understand why?
>
> I use
>
> : echo "SD8015002109 "|gdaltransform -s_srs EPSG:27700 -t_srs EPSG:4326
>
> which gives
>
> : -7.55729138544866 49.7667307394399 50.4807807941111
>
> If I use [1], the result is
>
> : 53.515279 -2.300819
>
> which can be verified as correct on maps.
>
> What error am I making in assuming this should work?
>
> I use
> GDAL 1.9.1, released 2012/05/15
> Fedora 17
>
> Thanks!
>
> Footnotes:
> [1]  http://www.nearby.org.uk/coord.cgi?p=SD8015002109&f=conv
>