Abstract
In this study, an improved coordinate transformation method between geodetic reference frames in Dubai, UAE, is investigated. In the first phase of this method, a similarity transformation is performed using a seven-parameter model between points known in the two frames involved in the transformation process. Next, the coordinate differences between the transformed coordinates and their known values in the frame into which they are transformed are computed. A database is then produced containing these coordinate differences. To transform coordinates of other points, their coordinates are initially transformed using the similarity transformation parameters estimated in the first step. Next, the coordinate corrections (as differences) at these points are interpolated using the generated database and added to the initial transformed coordinates. Instead of using the common method of double interpolation from a grid for this purpose, a new method is presented. The method directly interpolates coordinate differences at a required point from coordinate differences of the nearest three known points. These differences in the spatial domain form a triangle. Each triangle is assumed to be a surface. The coordinate difference at the required point is estimated on that surface by geometry. Results from testing show that coordinate transformation at accuracy of 2.1 cm on average was achieved in Dubai, which is better than using only the current traditional similarity transformation. Results also show that the proposed interpolation method has a very good performance.