[OSM-talk] Coordinate transforms
lists at lorp.org
Thu Apr 27 20:13:43 BST 2006
Thanks for that, Barry and Erik.
Since the accuracy is 7m (rather than 20cm), am I correct in thinking
that none of these methods incorporate the bilinear interpolation based
on the km square in which the point falls? Of course for GPS-related
stuff that might not be considered too important, but it seems to me
there's no point dropping accuracy if it's relatively easy to maintain it.
Barry Hunter wrote:
> There is links to various PHP/Perl/JS code here:
> nearly all converted from the gps.gov.uk information.
> These use the Hermert Transformation, with a typical accuracy of about
> 7m I believe for most of GB. Irish gets better at about 2m.
> For an online batch converter checkout
> uses the definitive OSTN02 transformation.
> Or the one at www.gps.gov.uk (no longer requires you to login)
> I don't think there are any issues of IP after conversion. However
> technically any coordinates in OSGB36 could be an issue as there is some
> debate if the BNG is itself copyrighted, but as its just a means of
> specifying a position its a real world fact. (A database of points could
> be copywrited as that is a 'work', as such its the database of postcodes
> that copywrited not the individual postcodes)
> Hope that helps
> - www.nearby.org.uk - www.geograph.org.uk - www.trigtools.co.uk -
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