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. Tim _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
