STUDY OF ABSOLUTE GEOIDAL UNDULATIONS AND DEFLECTIONS OF THE VERTICAL USING A CORRELATION METHOD

Abstract

The objective of this work was to develop a general method, based on the correlation principle to determine the absolute orientation vector of a non-geocentric geodetic system, utilizing the available heterogeneous data in the form of gravimetric, astrogeodetic and dynamic geoidal undulations and deflections of the vertical. Chapter 1 presents a general introduction of the work contained in this thesis, exposing the objectives and the motivation behind it. The second chapter deals with the gravimetric determination of the absolute values of the geoidal parameters, N, £ and "n. at the Indian geo detic datum, Kalianpur, H.S. This was carried out to provide a check for assessing the accuracy of results obtained through other methods employed here. To further improve the accuracy of this determination, some of the less reliable anomalies in the neighbourhood of Kalianpur, were replaced by estimated values from the least-squares prediction utilizing local autocovariance functions and known observed gravity anomalies in the area. Chapter III presents an application of the leastsquares solution technique for obtaining the absolute orientation of a geodetic datum even when a detailed knowledge of the gravity anomaly field in the neighbour hood of the computation point is not available. This method was applied to the Indian geodetic system in a more rigorous manner in order to ascertain the closeness of the values so computed, to those obtained gravimetrically. The development of the correlation method itself is presented in Chapter IV as well as its satisfactory appli cation to the Indian,. European and Russian geodetic ddtums, thereby demonstrating its general applicability to any geodetic system of the globe. Chapter V summarises the various results along with their analyses and estimates of their accuracy.