Transformations and OSGM02 user guide - Leica Geosystems

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Appendix A Transforming ETRS89 GPS coordinates to OSGB36 and orthometric height.....................................................................................29Worked example...........................................................................................................................................................................29Inverse transformation: OSGB36 to ETRS89 ......................................................................................................................................32Worked example...........................................................................................................................................................................32Appendix B Converting latitude and longitude to easting and northing ................................................................................................................33Worked example using the Airy 1830 ellipsoid and National Grid .....................................................................................................36Appendix C Converting easting and northing to latitude and longitude ................................................................................................................37Worked example using Airy 1830 ellipsoid and National Grid ...........................................................................................................39Appendix D Glossary .............................................................................................................................................................................................40Transformations and OSGM02 user guide contentsv2.1 9/2002 © crown copyrightPage 5
Chapter 1IntroductionCoordinate transformations and the Geoid modelAll Ordnance Survey mapping relates to a coordinate reference system. In Great Britain Ordnance Survey coordinatesrelate to OSGB36 ® (the National Grid); within Northern Ireland and the Republic of Ireland the coordinate referencesystem is the Irish Grid. These reference systems are traditionally realised on the earth's surface by monumentedtriangulation stations. The users of mapping products, in both the public and private sectors, have invested ingeographical information systems (GIS) and asset management systems based on these grid systems, which havebeen accepted as de facto national standards.The National Grid and the Irish Grid are capable of supporting surveying and mapping in UK and Ireland to meet all therequirements of users both now and in the future; however, an increasing number of spatial datasets are available inGPS (Global Positioning System) coordinate systems. When two or more coordinate datasets are to be integrated, it isessential that each relates to the same coordinate reference system, irrespective of accuracy issues.In order to relate GPS-derived positions to Ordnance Survey's mapping, GPS coordinates need to be converted to IrishGrid or to National Grid, which requires a specialised datum transformation. For this reason the Ordnance Survey ofNorthern Ireland and Ordnance Survey Ireland have developed a polynomial transformation, which is the standarddatum transformation for use throughout Ireland. The Ordnance Survey of Great Britain has developed OSTN02, thestandard datum transformation for Great Britain.Ordnance Survey mapping also includes height information that relates to a regional vertical datum. Height informationin Great Britain refers to Ordnance Datum Newlyn (ODN), which is established from mean sea level. Although ODN isthe national height datum used across mainland Great Britain there are a number of additional datums that are used onthe surrounding islands, for example: Lerwick on the Shetland Islands; Stornoway on the Outer Hebrides; St Kilda;Douglas02 on the Isle of Man and St Marys on the Scilly Isles. The Ordnance Survey of Northern Ireland relates heightswithin Northern Ireland to Belfast Lough datum, and Ordnance Survey Ireland relates heights within the Republic ofIreland to the Malin Head datum.Transformations and OSGM02 user guide chapter 1v2.1 9/2002 © crown copyrightPage 6
Page 2 and 3: PrefaceThis grid transformation sof
Page 4 and 5: Data copyrightUser guide copyrightT
Page 8 and 9: Orthometric heights in these system
Page 10 and 11: ETRS89 explainedBenefitsOrdnance Su
Page 12 and 13: Chapter 2Data overviewBasic princip
Page 14 and 15: Where:1 the record number is a sequ
Page 16 and 17: Where:1 the record number is a sequ
Page 18 and 19: 4 the height of the Geoid above the
Page 20 and 21: For example, to find the record for
Page 22 and 23: Shifts for x, y are:se 0= east_shif
Page 24 and 25: The OSi/OSNI polynomial transformat
Page 26 and 27: The Ordnance Survey Geoid model: OS
Page 28 and 29: Chapter 4Quality statementCoverageO
Page 30 and 31: Appendix ATransforming ETRS89 GPS c
Page 32 and 33: The offset values are given by:dx =
Page 34 and 35: Appendix BConverting latitude and l
Page 36 and 37: ⎛ ⎛ 5 2 5 3 ⎞ ⎛2 21 3 ⎞
Page 38 and 39: Appendix CConverting easting and no
Page 40 and 41: Worked example using Airy 1830 elli
Page 42 and 43: Geoid modelA model of the level sur

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