Figure 1-19. Astro-Geodetic Datum Orientation
(3) Gravimetric Method. If the relative deflections of the vertical at the initial point and the
Laplace stations of a triangulation net could be replaced by absolute deflection components, the
contradictions with similarly corrected adjoining surveys would be eliminated. Thus, the positions of
unconnected surveys would be coordinated. The absolute deflections of the vertical and the absolute
undulation of the geoid can be determined by the gravimetric method.
(a) Use the following procedures to obtain the absolute gravimetric orientation for a
triangulation net:
Compute the geoid's absolute gravimetric height and deflection of the vertical for the
initial point of the geodetic system. To obtain a more reliable result, the same
absolute quantities should be computed for several Laplace stations in the vicinity of
the origin.
EN0593
1-30
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