This book try to investigate the procedure forcombining heterogeneous data for modelling of thegravity data. Advanced methods based on theleast-squares modification of Stokes's approach isinvestigated for local geoid modelling. Inversegravity modelling for estimation of the crustal depthmodel is illustrated in details with the numericalcase studies. Also, application of satellitealtimetery data in modelling of mean sea level andheight datum estimation is explained in details. Thisbook can be used in post graduate degree programs ofgeodesy, geomatics, geophysics and oceanography.