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Michael Cramer
4 CONCLUSIONS
The presented results proved the high quality of direct exterior orientation measurements using highly sophisticated
integrated GPS/inertial systems in a standard photogrammetric environment. For some parts of the photogrammetric
production line (e.g. ortho image generation, flexible block design, initial data acquisition in remote areas) this
technique offers high benefits for time and cost reduction. Nevertheless, an overall system calibration problem still
remains. Although special calibration sites are imaginable where the integrated system (camera and orientation module)
is calibrated optimally within certain time intervals, the precise transfer and correctness of the calibrated parameters for
the actual operation area cannot be guaranteed. If very high accuracy applications within a few cm in object space are
aspired, the error budget of uncorrected systematic errors is at least of the same size as the influence of GPS/inertial
position and attitude variations assuming a proper system installation. Since these systematic effects are mainly due to
environmental aspects like changes in temperature, pressure, atmospheric refraction and therefore dependent on local
and time variations their sufficient a priori modeling is not possible. Only the re-introduction of AT offers this self-
calibration capability to determine the specific systematic error behaviour for a distinct area. Since the orientation
parameters are almost known from GPS/inertial integration, the computational burden (i.e. block preparation,
approximation values, tie point matching) is significantly less compared to a standard AT. Therefore, this combined
GPS/inertial AT is the most reliable, flexible and accurate approach and thus should be recommended for highest
photogrammetric accuracy demands.
ACKNOWLEDGEMENTS
The authors would like to thank the Survey State Offices (LVA) from Baden-Württemberg, Bayern, Nordrhein-
Westfalen, Niedersachsen and the State Office of Cartography and Geodesy (BKG) for providing the GPS reference
data. Special thanks needs to be expressed to Werner Schneider and Antje Quednau from ifp for their contributions and
excellent work.
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