Two-dimensional national datum transformation model

The widespread use of ED50 and ITRF96 datums in various institutions and projects across Türkiye necessitates a highly accurate transformation between these coordinate systems. Existing practices often rely on regional transformation parameters derived from a limited number of common points at local scales. However, this approach presents several challenges, including the need for densification of common points, difficulties in parameter acquisition, and varying transformation accuracies. To address these issues, the National Datum Transformation Model (UDDM) was developed, aiming to offer a homogeneous, high-accuracy transformation across Türkiye without requiring users to supply transformation parameters. A raw dataset consisting of 4,200 groups and 62,500 points was analyzed, leading to the identification of 7,313 high-reliability common points after rigorous cleaning and validation. Using these points, the TUM Model was developed within the Lambert Conformal Conic projection, which does not require zone transformation. The TUM Model was tested in MATLAB, yielding a maximum RMSE of ±3 cm with two-dimensional transformation models. Additionally, three alternative models were developed: the TUTGA Model (611 points TUTGA points), the CORS Model (181 TUSAGA-Active points), and the ML Model utilizing machine learning algorithms. All models were evaluated with statistical methods. UDDM integrates the most accurate results on a point-by-point basis, offering a flexible, reliable, and sustainable solution with an overall RMSE within ±9 cm across the country.