Spectra Precision Survey Pro v3.80 Ranger GPS User Manual - Manual (Page 49)

RTK Data Collection
45
Vertical Calibration and Geoid Modeling
If you do not use a geoid model, vertical localization will solve for
slope and separation using the measured heights and the control
elevations. If you do use a geoid model, vertical localization will solve
for the separation between the geoid elevation and your control
elevation. Geoid elevations are computed from measured heights and
geoid undulation using the height equation (see page 14):
h = H + N
Quality of Localization Solution:
Starting from an autonomous GPS base position and solving a
Localization with control points is like starting a conventional survey
from an unknown setup and solving a resection. The quality of the
solution depends on both the precision of the measurements to the
control points and the accuracy of the control point coordinates.
When solving a Localization with control points, the following
guidelines should be followed:
•
Quality of control points: the control point coordinates should be
at least as precise as the specified survey requirements.
Fig. 9: Vertical Localization
Three control points calculate a plane to model the deflection and shift
between the geoid and ellipsoid surface.
Ellipsoid
Surface
Geoid Surf
ace
Separation
Normal
to Geoid
Normal to
Ellipsoid
Deflection (a,b)