I parametri di trasformazione tra il sistema WGS84 ed il sistema geodetico nazionale Roma40

In this paper the procedure used at the Geodetic Department of the Istituto Geografico Militare Italiano to derive the transformation between WGS84 and the italian national Datum Roma40 is described. The procedure is based on the local estimation of the 7 parameters in the Molodensky transformation model - derived from the linearization of Helmert model - which allows to deal with planimetric and altimetric data separately. The geometrical meaning of the parameters is discussed with reference to the size of the application area, using numerical tests. The application of the above procedure to the connection between the new fundamental, GPS-determined, geodetic network IGM95 and the classical network Roma40 is finally illustrated.