Transformations and OSGM02 user guide - Leica Geosystems

Shifts for x, y are:se 0= east_shift(east_index, north_index)NOTE: recall that the record number in the data file will be (east_index+(north_index x 701) + 1)se 1= east_shift(east_index + 1, north_index)se 2= east_shift(east_index + 1, north_index + 1)se 3= east_shift(east_index, north_index + 1)sn 0= north_shift(east_index, north_index)sn 1= north_shift(east_index + 1, north_index)sn 2= north_shift(east_index + 1, north_index + 1)sn 3= north_shift(east_index, north_index + 1)Offsets are:dx = x – x 0dy = y – y 0The value of the east shift (se), north shift (sn) at the point x, y is given by the following formulae:t =dx /1 000u =dy /1 000se =(1 – t)(1 – u) se 0+ ( t)(1 – u) se 1+ ( t) ( u)se 2+ (1 – t)( u) se 3sn =(1 – t)(1 – u) sn 0+ ( t)(1 – u) sn 1+ ( t) ( u)sn 2+ (1 – t)( u) sn 3These shifts must then be added to the point x, y to give the National Grid position (e, n):e = x + sen = y + snTransformations and OSGM02 user guide chapter 3v2.1 9/2002 © crown copyrightPage 21