[Talk-GB] OS Boundaries

Andrew Chadwick (email lists) andrewc-email-lists at piffle.org
Tue Apr 20 10:08:57 BST 2010

Chris Hill wrote:
> I've been taking a look at the boundary data released as part of the
> OS bundle. I've put together a little script that will extract a
> named boundary as an OSM file ready for loading into JOSM. OS data
> uses the OS projection and we use the WGS84 projection. I used
> ogr2ogr to transform the data from one to the other, but there seems
> to be a bug with its handling of the OS data projection. The
> resulting OSM way is the correct size and shape, but is not in quite
> the right place. The discrepancy in location varies across the UK, so
> a fixed correction will not work. The variation between individual
> nodes will be too small to matter in a parish boundary, but might be
> a problem for the biggest counties.

I've had a degree of success with
http://search.cpan.org/~toby/Geo-Coordinates-OSGB-2.04/ - I've used
these packages in the past for rectification of OOC OS stuff and
conversion of many-figure OS grid refs with a good degree of success. Do
you get the same positional results with this? Does applying the OSTN02
transform too make any difference?

Andrew Chadwick

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