datum 
W0: an estimate in the Finnish Height Datum N60, epoch 1993.4, from twentyfive GPS points of the Baltic Sea Level Project


It is well known that for the comparison and combination of geodetic networks their heterogeneous datum definitions are well to be considered.


As an alternative concept to deal with hybrid datum problems, the operator parallel sum of matrices is introduced in this paper.


The second one treats the estimation of parameters representing the heterogeneous datum definitions of two networks which are to be merged into a hybrid network.


It will be shown that  regardless of the datum definitions of the preadjusted individual networks  the parallel sum of matrices can be used to simplify the algorithms applied for the estimation of those parameters.


We also found JGM3 Geosat orbits have not resolved the datum errors evident from the JGM2 Geosat T/P results.


Generalized inverses of nonlinear mappings and the nonlinear geodetic datum problem


The datum for the Kalman filter is introduced at the zero epoch by the choice of a generalized inverse.


On an islandbyisland basis, CARIB97 now offers the ability to analyze local datum problems which were previously unrecognized due to a lack of highresolution geoid information in the area.


The 2 arcminute × 2 arcminute geoid model (GEOID96) for the United States supports the conversion between North American Datum 1983 (NAD?83) ellipsoid heights and North American Vertical Datum 1988 (NAVD?88) Helmert heights.


A separate geocentric gravimetric geoid, G96SSS, was first calculated, then datum transformations and leastsquares collocation were used to convert from G96SSS to GEOID96.


Robust estimation of geodetic datum transformation


The robust estimation of geodetic datum transformation is discussed.


A numerical example is given on a datum transformation between a global positioning system network and the corresponding geodetic network in China.


The two main types of `unknowns' in this kind of multidata 1D networks are usually the gravimetric geoid accuracy and a 2D spatial field that describes all the datum/systematic distortions among the available height data sets.


An accurate knowledge of the latter becomes especially important when we consider employing GPS techniques for levelling purposes with respect to a local vertical datum.


Other problems are related to free geodetic datum parameters, most of all the vertical datum, overdetermination or additional constraints imposed by satellite geodetic observations or models.


Altimetrygravimetry problems with free vertical datum


A numerical solution strategy for the freedatum problem is presented.


A review of algebraic constraints in terrestrial reference frame datum definition

