Deriving transformation parameters for existing survey co-ordinate systems in the Australian Capital Territory

Abstract

[Abstract]: This project investigates and evaluates the use of the conformal, affine and projective transformation methods to derive parameters to convert three existing co-ordinate systems found within the Australian Capital Territory into the Geodetic Datum of Australia 1994 map projection Map Grid Australia. These existing co-ordinate systems are known as City Co-ordinates (CC), Preliminary Grid Co-ordinates (PGC) and Adjusted Grid Co-ordinates (AGC) and are located in separated zones through the ACT. Three styles of transformation have been used in each of the three co-ordinate zones and analysis has been made into which method is most suited when a conversion from a 2D orthogonal co-ordinate system into another is required. Comparisons have also been made when using GPS observations and territory published values to derive parameters in converting values within each test area. Effects of extrapolation have been investigated to determine the magnitude of error when parameters are used outside the region used to derive them. The error from the effects of extrapolation, have also been contrasted against acceptable limits defined from class and order of known published values. Spatial information is at the forefront of industry and government and with the ever increasing quantity of available data to the spatial user, quality data is desirable and co-ordinate transformation offers a method to data users for the merging of data and co-ordinate system conversion within data sets.