Transformations and OSGM02 user guide - Leica Geosystems

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Chapter 2Data overviewBasic principlesSpecifications of OSTN02 horizontal transformationTransformation:Transformation type:Estimation method:Grid resolution:Grid interpolation:Accuracy:Extent:horizontal datum transformation between ETRS89 and OSGB36interpolated square grids of easting and northing shiftsDelaunay triangulation1 kmbilinear0.1 m (RMS) with respect to OSGB36 primary, secondary and tertiarytriangulation monuments700 km east by 1 250 km northSpecifications of OSi/OSNI polynomial transformationTransformation:Transformation type:Accuracy:Extent:datum transformation between Irish Grid and ETRS893rd order polynomial0.4 m (95% of data)Republic of Ireland and Northern IrelandSpecifications of OSGM02 Geoid modelTransformation: vertical ETRS89 ellipsoid to orthometric heightTransformation type: interpolated square grid of geoid heights above ETRS89 ellipsoidEstimation method: Spherical Fast Fourier transformation with modified Stokes kernelsGrid resolution: 1 kmGrid interpolation: bilinearAccuracy: Area specific: Mainland GB 2 cm rms,Republic of Ireland 3 cm rms,Northern Ireland 2 cm rms, with respect to Ordnance Survey BMs,Transformations and OSGM02 user guide chapter 2v2.1 9/2002 © crown copyrightPage 11
Data structureOSTN02/OSGM02 within Great Britain – format and layout of the dataWithin Great Britain OSTN02 and OSGM02 are released as a combined data file using the same 1 km grid. This gridcovers an area 700 km east–west and 1 250 km north–south, the origin being the origin of the projected ETRS89coordinates (see appendix B). However, the area to which the models are valid has been cookie cut to a 10 km polygonbeyond the coastline. This means that any position more than 10 km offshore will have fields 4, 5, 6 and 7(see below) all set to zero.It is strongly recommended that the transformation software be written to return an outside transformationboundary type error when a point outside this area is encountered.Each record occupies a separate line with the south-west corner of the grid being the first record in the file. The formatof each record is indicated by the following table:Record no 1ETRS89easting 2 (m)ETRS89northing 3 (m)OSTN02 eastshift 4 (m)OSTN02 northshift 5 (m)OSGM02Geoid Ht 6 (m)Geoiddatum flag 71 0 02 1 000 03 2 000 0and so on and so on and so on701 700 000 0702 0 1 000703 1 000 1 000704 2 000 1 000and so on and so on and so on876 948 697 000 1 250 000876 949 698 000 1 250 000876 950 699 000 1 250 000876 951 700 000 1 250 000Transformations and OSGM02 user guide chapter 2v2.1 9/2002 © crown copyrightPage 12
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 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

Transformations and OSGM02 user guide - Leica Geosystems

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