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Operating Instructions on the Rover Unit
Refining the coordinate system by surveying reference points
Refining the coordinate system by
surveying reference points
When the work area includes reference points whose locations are
accurately known in the coordinate system you have to use, and on
the other hand some of the characteristics of this coordinate system
are not precisely known, then you can rely on the surveying of these
points to refine the definition of the coordinate system.
This kind of computation can be performed either by the rover unit
or, when back at the office, by the KISS module of 3SPack. Refer to
the 3SPack Reference Manual or to the On-Line Help file of the
KISS module for more information about geodetic choice issues.
When surveying a point, basically the rover unit computes the
coordinates of this point on the WGS84. Then computations are run
to transform these WGS84 coordinates into coordinates expressed
on the chosen datum and projection.
If we assume that both the "theoretical" coordinates of a reference
point expressed in the partially unknown system and the surveyed
WGS84 coordinates for the same point are error-free, then the rover
unit can refine the coordinate system used so that the "theoretical"
coordinates of the point be precisely the coordinates obtained by
transforming the surveyed WGS84 coordinates using the refined
coordinate system.
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Two kinds of computation can be performed in the rover unit:
- refining the horizontal system (local grid)
- or/and refining the vertical system (height correction)
When preparing a job with KISS, if reference points are created for
the purpose of refining the coordinate system used, then follow the
instructions below to refine the coordinate system.
Note that a third type of computation is possible using reference
points surveyed by the rover unit. The purpose of this computation,
which can only be performed with KISS when back at the office, is to
refine the datum shifts of the system used (if it is a standard one).
DSNP
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