APPLICATION OF 2D TRANSFORMATION MODELS FOR THE CONVERSION OF HISTORICAL TOPOGRAPHIC PLANS FROM SOROCA CITY, REPUBLIC OF MOLDOVA

Abstract

The integration of historical geodetic data into the national spatial data infrastructure represents an essential step for valorizing cartographic heritage and ensuring the interoperability of modern reference systems. The present study has as its main objective the transformation of coordinates from the local Soroca system, historically used on the territory of the Republic of Moldova, into the national coordinate system MOLDREF99, compatible with European Terrestrial Reference System 1989 (ETRS89). The proposed methodology is based on the application of 2D mathematical transformation models — Helmert (4 parameters) and Affine (6 parameters) — for the conversion of topographic plans at scale 1:500 from Soroca city. Twelve common geodetic points were used, identified both on vectorized plans and in the national GeoData database, and the transformation parameters were calculated using the least squares method and validated on eight independent points. The comparative analysis demonstrated that both models offer similar precision, with mean square errors of approximately 0.002 m and RMSE (Root Mean Square Error) of 0.0226 m in the X direction and below 0.008 m in the Y direction, values that fall within acceptable limits for cadastral and topographic works at scale 1:500. The obtained results demonstrate the feasibility of coordinate transformation without direct field measurements, using exclusively existing cartographic resources and the national geodetic database, thus contributing to the development of the National Spatial Data Infrastructure (NSDI) and the valorization of cartographic heritage for cadastral applications, territorial planning, and urban development.