Transformations and OSGM02 user guide - Leica Geosystems

More documents

Recommendations

Info

4 the height of the Geoid above the ETRS89 ellipsoid, in metres, at the intersection, that isETRS89 height – OSGM02 Geoid height = orthometric height above mean sea level.5 the Geoid datum flag is a number from 1 to 14, representing the geoid datum to which OSGM02 Geoid heightrelates, for example, this flag is 13 for Malin Head, the orthometric height datum used in the Republic of Ireland.See table 1 below for details of other datum flag references.Table 1Geoid datum flag Datum name Region0 N/A Outside model boundary1 Newlyn UK mainland2 St Marys Scilly Isles3 Douglas02 Isle of Man4 Stornoway Outer Hebrides5 St Kilda St Kilda6 Lerwick Shetland Isles7 Newlyn Orkney Isles8 Fair Isle Fair Isle9 Flannan Isles Flannan Isles10 North Rona North Rona11 Sule Skerry Sule Skerry12 Foula Foula13 Malin Head Republic of Ireland14 Belfast Northern IrelandNOTE: If the datum flag indicates a zero (0) then the coordinate falls more than 10 km offshore or 2 km beyond theNorthern Ireland/Republic of Ireland border and is not covered by the model.Transformations and OSGM02 user guide chapter 2v2.1 9/2002 © crown copyrightPage 17
Chapter 3Ordnance Survey transformations and OSGM02 explainedThis chapter explains the algorithms that must be coded to implement the Ordnance Survey transformations (OSTN02and the OSi/OSNI polynomial) and OSGM02.OSTN02Transforming ETRS89 coordinates to OSGB36 National Grid: overviewTo transform an ETRS89 value to OSGB36, the ETRS89 easting and northing is first obtained using the algorithm,GRS80 ellipsoid parameters and National Grid projection parameters in appendix B. Within the kilometre square wherethe point falls, a bilinear interpolation is used to obtain the exact transformation value for the point from the values at thefour corners of the kilometre square. These values are added to the ETRS89 easting and northing to obtain the OSGB36values. The inverse transformation (OSGB36 to ETRS89) is accomplished by an iterative procedure.Calculating which data record to useTo find the record number corresponding to a given ETRS89 easting and northing, use the following algorithm:east_index = integer_part_of (easting/1 000)north_index = integer_part_of (northing/1 000)record_number = east_index + (north_index x 701) + 1Transformations and OSGM02 user guide chapter 3v2.1 9/2002 © crown copyrightPage 18
Page 2 and 3: PrefaceThis grid transformation sof
Page 4 and 5: Data copyrightUser guide copyrightT
Page 6 and 7: Appendix A Transforming ETRS89 GPS
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 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

Transformations and OSGM02 user guide - Leica Geosystems

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?