The observation equations must be given weights Pa = 097/03?
where cog refers to the weight unit of the photogrammetric
observations.
The observation equations tie in with the block-adjustment
via the common unknowns Xg:;, Yoj» Zoj» Wj, $j, Kj appearing
in the (bundle-) block-adjustment. They give' in “first in-
stance additional diagonal terms for the normal equations
which are easily computed (and maintained in the reduced nor-
mal equations). The unknown parameters A0» 224 35<+ »:f0a fi
will independently take care of datum transfer and drift,
including other possible systematic errors. They will modify
the reduced normal equations to banded-bordered matrices
which most block-adjustments programs are prepared to cope
with already now. It is assumed that the additional para-
meters can be solved, if at least some ground control points
are available. It will have to be investigated, however,
whether linear terms will be sufficient and by what overlap-
and control configurations they can be determined in the
combined block-adjustment. Datum and drift terms are expres-
Sed here as functions of Xx along the flight axis. Approximate
coordinates X are sufficient. They may also be available di-
rectly from the navigation data or from continuous Doppler
speed recordings.
Preliminary considerations suggest that the auxiliary data
may be treated, as first approach, as uncorrelated observa-
tions. It will have to be established by experimental in-
vestigations whether more intricate error properties will
have to be taken into account, which is technically possible.
It is not compulsory for the combined adjustment that auxili-
ary observations must be given for all 6 orientation para-
meters of each camera station. For instance GPS will directly
give only position data. Also, it can be anticipated that
attitude data will be effective only if they reach a certain
accuracy level. As the case may be, some of the above equa-
tions may be deleted, leaving the respective orientation para-
meters to be solved in the conventional way by the block-
adjustment.
4. NAVIGATION DATA FOR AERIAL TRIANGULATION
4.1 Considering the technical development of navigation
systems it can be expected that rather soon quite precise
navigation data will become available. It is time, therefore,
that photogrammetrists prepare themselves for this new
situation.
It is of prime interest to consider first the effects of
navigation data on the combined adjustment in aerialtriangu-
lation. From the experience with statoscope it is known that
auxiliary data are highly effective in the combined block-
adjustment even if their accuracy is only moderate compared
to the photogrammetric measuring precision. The adjusted block
is considerably more accurate than the auxiliary data alone
would suggest. This experience has been confirmed with Xy-
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