On 19 Oct 2009, at 23:19, TimSC wrote: > Thomas Wood wrote: >> Good luck, this is the one projection that the OS actually sell for >> professional uses. >> >> I thought that OSTN02 wouldn't actually be needed unless for the very >> high precision stuff. The standard OSGB36 transform should be good >> enough otherwise? > I don't think they are that restrictive. They seem to have a freeware > library and API for windows (closed source) here > http://www.ordnancesurvey.co.uk/oswebsite/gps/osnetfreeservices/furtherinfo/questdeveloper.html > > On accuracy, converting NR730100 to ETRS89, > > OSTN02: 55.33149630, -5.58040715 > Helmert (based on OS spreadsheet[1], ported to C++): 55.331258, > -5.580440849 > Nearby.org.uk: 55.331495, -5.580444 > http://www.rutter.uklinux.net/ostowiki.html: 55.33149480 -5.58044426 > Streetmap.co.uk: 55.331967, -5.579682 > ganzc (by Chuck Gantz): 55.3314950512,-5.58040512526 > > [1] > http://www.ordnancesurvey.co.uk/oswebsite/gps/docs/ProjectionandTransformationCalculations.xls > > First observation: there is a range of accuracies from various > sources! > ganzc was better than I remember. I will investigate that one further.
Not sure it'll be any use but Multimap have (or at least had) a REST API that I think does this conversion. A while since I've had anything to do with it but you might want to take a look and see if it helps: http://blog.multimap.com/2008/06/20/new-open-api-features-in-time-for-mashed-08/ John _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
