More info about systems in use in UK is at: http://www.ordnancesurvey.co.uk/oswebsite/gps/information/coordinatesystemsinfo/guidecontents/guidea.html PROJCS["OSGB 1936 / British National Grid", GEOGCS["OSGB36", DATUM["OSGB36", SPHEROID["Airy 1830",6377563.396,299.3249646, AUTHORITY["EPSG","7001"]], TOWGS84[446.448,-125.157,542.06,0.1502,0.247,0.8421,-20.4894], AUTHORITY["EPSG","6277"]], PRIMEM["Greenwich",0.0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.017453292519943295], AXIS["Geodetic latitude",NORTH], AXIS["Geodetic longitude",EAST], AUTHORITY["EPSG","4277"]], PROJECTION["Transverse_Mercator", AUTHORITY["EPSG","9807"]], PARAMETER["central_meridian",-2.0], PARAMETER["latitude_of_origin",49.0], PARAMETER["scale_factor",0.9996012717], PARAMETER["false_easting",400000.0], PARAMETER["false_northing",-100000.0], UNIT["m",1.0], AXIS["Easting",EAST], AXIS["Northing",NORTH], AUTHORITY["EPSG","27700"]] The definition with 3-parameter transformation: PROJCS["OSGB 1936", GEOGCS["OSGB 1936", DATUM["OSGB_1936", SPHEROID["Airy 1830",6377563.396,299.3249646], TOWGS84[375,-111,431,-0,-0,-0,0]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",49], PARAMETER["central_meridian",-2], PARAMETER["scale_factor",0.9996012717], PARAMETER["false_easting",400000], PARAMETER["false_northing",-100000]] There is also definition merged with the Newlyn height: EPSG:7405 For higher accuracy transformation you can use the grid-shift files described here: http://lists.maptools.org/pipermail/proj/2006-November/002658.html More information about different coordinate systems used in UK have a look at the tools PROJCS["TM65 / Irish Grid", GEOGCS["TM65", DATUM["TM65", SPHEROID["Airy Modified 1849",6377340.189,299.3249645999944, AUTHORITY["EPSG","7002"]], TOWGS84[482.5,-130.6,564.6,-1.042,-0.214,-0.631,1.6810581709138355], AUTHORITY["EPSG","6299"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4299"]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",53.5], PARAMETER["central_meridian",-8], PARAMETER["scale_factor",1.000035], PARAMETER["false_easting",200000], PARAMETER["false_northing",250000], UNIT["metre",1, AUTHORITY["EPSG","9001"]], AUTHORITY["EPSG","29902"]] |
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