VERIFICATION OF GEODETIC POINTS USING GPS MEASUREMENTS

frame; b) the material point defined by the physical mark of this geodetic point. These two points should be geometrically id entical in horizontal plane (2D) or space position (3D). They have but really diffe rent (non-coincidence) relations at each geodetic point. The reliable differences be tween the both positions a), b) can be expressed by the coordinate differences (d iscrepancies) dC=C´-C i.e. [dX dY dZ]= [X´Y´Z´]-[XYZ] between the poi nt coordinates C from the database and from the present measurements C´.The differences dC at points can reach values from some mm up to unacceptable values of some cm. In the contemporary geodetic networks (epoch t´) there are always some points which do not already fulfil the compatibility requirements. This is typical above all for the networks established and concentrated in the past (epoch t). Point uncompatibility, that indicates properly its inapplicability in the present, can be caused e.g. owing to unaccurate coordinate determination in epoch t, point carrier movements in the period t´ - t, various datum influences and other causes. It is therefore necessary always to ve rify all the "given" po ints before their use in the present geodetic activities and to employ the compatible points only. The use of incompatible points in a netw ork adjustment causes a lot of biased coordinate estimates whose id entification in the results re presents a cumbersome and uncertain task that has any unified methodical solution. VERIFICATION PRINCIPLES OF POINT COMPATIBILITY Plane or space differences among the coordinates of geodetic points and their marks can be acceptably described by differe nces dC between their 2D or 3D known coordinates C from epoch t and their coordinates C´ determined in epoch t´ .These coordinate differences (discrepancies, "residuals" in the competent adjustment processes) can be explained by relations dC = C´– C = [X ,Y]´- [X ,Y]=[X´-X ,Y´-Y]=[dX ,dY] (1) dC = C´– C = [X ,Y, Z]´- [X ,Y ,Z]=[X´-X, Y´-Y ,Z´-Z]=[dX, dY, dZ], and the quantities dC can be taken as in dicators of point compatibility. Using for apreciation of the vector dC reliable deci sion procedures based on probability theory International Conference of Modern Management of Mine Producing, Geology and Environmental Protection