The aim of this investigation
is to study how to use a
gravimetric (quasi) geoid for levelling
by GPS data in an optimal
way. The advent of preci~ gex-xJetic
GPS has made the use of a technique
possible, which might be
called GPS- gravimetric geoid detemfination.
In this approach, GPS
heights above the reference ellipsoid
are determined for points
whose levelled ( orthometric )
height H is above ~ level people
have already surveyed; for these
points, we thus have the values of
the geoid undulation N. These values
are then used to constrain the
geoid undulations N".