introduced into the BINGO-F adjustment. This
unknown stands in the BINGO-F adjustment until a
new (resolved or unresolved) ambiguity occurs for
this satellite.
This yields to one additional unknown to be
estimated in BINGO-F for every ambiguity that was
left unresolved from GEONAP. In the worst case
GEONAP cannot solve any ambiguity. In this case
the maximum number of unknowns is one unknown
per satellite and one additional unknown for each
cycle slip occurred. In the best case, when
GEONAP has solved all ambiguities, no additional
unknown has to be carried along in BINGO.
Fig. 2 Eccentricity e’
from the projection center to the antenna
The last step after the computation of the aircraft's
GPS antenna position is the interpolation of the
camera exposure events between the GPS
exposure events. The reduction from the GPS
antenna position to the camera’s projection center is
also done in this step. BINGO-F enables the
estimation of the vector e’ from the projection
center to the antenna (see Fig. 2) as additional
unknown in the adjustment process.
In most cases it suffices to derive the current
orientation of the aircraft platform from the GPS
trajectory. Sometimes it may be useful to take
additional information into account for this purpose,
e.g. from aircraft sensors. The interpolation should
consider changes in the satellite configuration and
unresolved cycle slips during the interpolation
interval.
398
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996
6. Example
Let us assume a configuration of 7 satellites, a
smooth flight with no cycle slips, and a flight of 4
strips. Let us assume additionally that all the
ambiguities are left unresolved. With the usual
approach there are 6 additional unknowns to be
estimated per strip: 3 shift and 3 drift parameters.
This yields to 24 additional unknowns for the flight.
With the new approach, only 6 additional ambiguity
parameters for the 7 satellites (one is linear
dependent on the 6 others) have to be estimated for
the whole flight.
7T. Conclusions
Advantages of the new approach:
e only a minimum of required parameters have to
be estimated.
e noinformation in the GPS adjustment is lost.
e the mathematical model is functionally correct,
— no problems with possible non linear
configurations.
e the ambiguity resolution is possible in iterative
steps, first in GEONAP and second in BINGO-F,
and it is possible to use the additional
information from the photo measurements for
the sophisticated ambiguity search algorithms.
It can already be said today that this method will
gain acceptance due to economical reasons as
costs can be saved for each photogrammetric block
adjustment leading to a short pay-back period for
the software development.
8. Literature
Kruck, E. Lósung grof$er Gleichungssysteme für
photogrammetrische — Blockausgleichungen mit
erweitertem funktionalen Modell. Wissenschaftliche
Arbeiten der Fachrichtung Vermessungswesen der
Universität Hannover Nr. 128. Dissertation 1983.
Kruck, E. and Trippler, S.: Automatic Compu-
tation of Initial Approximations for Bundle Block
Adjustment with Program RELAX Optical 3-D
Measurement Techniques Ill, Vienna, October 1995
Wübbena, G.: Zur Modellierung von GPS-Beob-
achtungen für die hochgenaue Positionsbestim-
mung. Wissenschaftliche Arbeiten der Fachrichtung
Vermessungswesen der Universitát Hannover Nr.
168. Dissertation 1991.
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