Analytical Study of 3D Transformation Parameters Between WGS84 and Adindan Datum Systems in Sudan

Abstract

Coordinate transformation between various reference datums or systems is an essential tool in geospatial tasks such as surveying, geodesy and photogrammetry. Transformation of coordinates is a mathematical process that converts coordinates of a point in one reference datum into coordinates of the same point in the other reference datum. This issue is still critical for the earth sciences scholars in Sudan because the topographic maps were carried out based on the local datum (Adindan) and the recent surveying activities are performed using Global Positioning System, i.e., based on WGS84 reference datum. To resolve the transformation problem between the WGS 84 and Adindan datum systems, the current study explores two transformation methods, namely Bursa–Wolf and Molodensky–Badekas. The least squares observation equations and the combined case versions of Bursa–Wolf and Molodensky–Badekas are employed to estimate different transformation parameters. These parameters are tested and validated using coordinates of 32 first-order points known in both Adindan and WGS84 datum systems. The results are further verified by a statistical test. Through the residuals estimated, the suitability of the transformation methods for application in the study area is thoroughly discussed. To make survey data usable and accessible to all, it is essential to establish reliable transformation parameters where data collected in one system can easily be transformed into the other. Therefore, if the relationship between the WGS84 and Adindan (local) reference systems is accurately established and verified by higher quality control indices, we can promote mapping and other survey activities in Sudan. Again, Sudan has a large and extensive local network. This network can be easily reduced to the worldwide platform if the transformation parameters between the two systems are precisely estimated.