Integrating Syrian Cadastral Data into Digital Twins Through Accurate Determination of Transformation Parameters

Syria is a developing country adopting the local datum known as clarke1880 for all surveying and mapping activities. Currently, for all numerical maps and digital models in Syria, the use of satellite positioning technology is needed and mainly for geodetic applications using Global Navigation Satellite Systems (GNSS). The integration of Syrian cadastral data into digital twins is essential for the country construction and infrastructure projects. Therefore, the establishment of a functional relationship between the Clarke 1880 and GNSS reference datum is necessary. The problem is in one hand, the absence of accurate transformation parameters from GNSS data into the Syrian Cadastral system. In another hand, the insufficiency of geodetic network reference points in the region severely hinders attempts to make use of GNSS; some of these points have issues due to vacancies in the region while others have been damaged or lost entirely over the years. In this study, the least squares method is applied on a set of 100 points distributed across the area of Syria, to obtain the 7-transformation parameters whose global and local geocentric coordinates are known and then estimate their accuracy. These parameters were then used to transform geocentric coordinates of a set of 35 points, whose global geocentric coordinates are known, into the local geocentric coordinates. However, Syria’s national coordinate system is a projected grid coordinate, called the Syrian stereographic system (cadastral system), and thus the geocentric coordinates (X, Y, Z) on the local datum are not applicable. There is therefore the need to obtain these coordinates in the Syrian stereographic system. Statistical study of errors was carried out as well as the calculation and evaluation of the accuracy indicators to give finally necessary recommendations to integrate Syrian cadastral system in digital twins.