[Openstreetmap] Landsat Update = Datum Shift

[Nick Whitelegg]

On Monday 02 May 2005 08:16, Jeremy Stocks wrote:
> Took a look at your Southampton Water problem and the words Datum Shift
> immediately sprang to mind. I often have to solve these problems of old to
> new datums. (I am working on a Munich based GIS problem at the moment)
>
> I have spent a long time learning this stuff and am stil not expert at it.
> I warn you it is more complicated than it looks! If I had time I might be
> able to help. Sadly I do not! :(
>
> If you are editing OS data it is most likely to be in a very old
> "topocentric" datum or tie point between the map and the earth.
>
> GPS data is collected with reference to the centre of the earth or
> "geocentric" data.

Thanks for the info. Only thing is, I'm now using pure latitude/longitude
(WGS84) - no OSGB stuff - and still get the same error. Always a 100m offset,
or thereabouts, irrespective of the strength of the GPS signal. I suspect I'm
grabbing slightly the wrong bit of Landsat data....

Nick