Regional coordinate transformations

The main factor is coordinate systems in obtaining significant results from digital products such as plan, map etc produced for geodetic aims. Indeed, all coordinate informations have to be based on a joint reference system. But, different reference systems have been used in geodetic works performed regionally and locally. Turkish National Datum ? 1954 (TND54) has been defined in 1954. This datum has been transformed ED50. Because of the regional distorsions in Turkey, ED50 has been useless for the practical applications. A new national geodetic network based on GPS technology has been needed and the main geodetic network called Turkish National Fundamental GPS Network 1999 (TFGN99), has been established by using the measurements and processing works performed between 1997 and 1999. Since The Large Scale Map and Map Data Production Regulation has been became in to force in 2005, obtaining the spatial map data using 3D cartesian coordinates based on Turkish National Fundamental GPS Network (X, Y, Z), or the geodetic coordinates in GRS80 ellipsoid (latitude, longitude, ellipsoidal height).have been became obligatory. Because of the local governments have not enough information about the new coordinate system, it has not been realized to produce the spatial data according to the new coordinate system perfectly yet. Two different datums are used in practice in Turkey and it has became inevitable to determine the transformation between these datums (ITRF ? ED50). In this study, the datums which are used in our country and the coordinate transformations made among different coordinate systems in regional coordinate transformation studies, have been explained. For this aim, a study has been done in accordance with The Large Scale Map and Map Data Production Regulation in Gaziosmanpasa and different coordinate transformation methods in regional coordinate transformation studies have been examined. Keywords: Datum, transformation, coordinate transformation, ITRF, ED50.