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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B6. Istanbul 2004
6. CAMERA CALIBRATION AND VALIDATION
The Working Group on Calibration and Validation of CEOS
(The Committee on Earth Observation Satellites, an interna-
tional co-ordinating body comprising 23 Members, mostly
space organizations, and 21 Associates, national and interna-
tional organizations such as ISPRS, charged with co-ordinating
international civil space-borne missions designed to observe
and study planet Earth) has in connection with space sensors
accepted the following definitions:
e Calibration is the process of quantitatively defining the
system response to known, controlled signal inputs
e Validation is the process of assessing, by independent
means, the quality of the data products derived from the
system outputs.
It is obvious that the camera calibration procedures used for
aerial film cameras need significant extensions to deal with the
complexity of the digital cameras, and that different procedures
may be needed for each camera type. Hence, test-field
calibrations will play a significant role. Since the digital cam-
eras provided raw data in need of processing prior to being
useful, validating the digital image products will also be an
important step to be considered. EuroSDR has arranged a wor-
king group — the first author is a member of the group — with
two objectives:
e Collection of publicly available material on digital camera
calibration to compile an extensive report describing the
currently used practice and methods (Phase 1)
* Empirical testing with focus on the development of com-
monly accepted procedure(s) for camera calibration and
testing, based on the experiences and advice of individual
experts (Phase 2).
The first author is also a member of the working group on
international standardization of the German Society of Photo-
grammetry and Remote Sensing (DGPF). This group contrib-
utes to ISO projects such as ISO 19130 "Sensor and data mod-
els for imagery and gridded data" (which reached the commit-
tee draft level early this year) and to German standardization.
It is expected that the project will result in experiences helpful
in developing procedures for in-flight calibration and validation
of digital cameras.
7. CONCLUSIONS
The project was conceived in November 2001 knowing the
need for DTM data in support of investigations of vegetation
damages resulting from ground-water level changes. The flood
of August 2002 emphasized the need of the creation of DTM
data of sufficient accuracy and point density. Efforts to gain the
support of the state government failed in spite of very positive
expert opinions. It has since become apparent that the project
can only be realized if sponsors can be found for parts of it.
Several such sponsors now assure that the first two flight mis-
sions can be carried out during the autumn of 2004. However,
sponsors may wish to limit the distribution of project data; this
would not agree well to past practices of EuroSDR to make data
available to all interested members.
213
8. REFERENCES
CEOS - Committee on Earth Observation Satellites, 2004.
Working Group of Calibration & Validation,
http://wgcv.ceos.org/wgcv/wgcv.htm (accessed 22 Apr. 2004)
Cramer, M., 2003. Integrated GPS/inertial and digital aerial tri-
angulation — recent test results, Fritsch (ed.) Photogrammetric
Week 2003, Herbert Wichmann, Heidelberg, Germany, pp.
161-172
EuroSDR-Project Homepage Comprehensive Test of modern
digital photogrammetric data acquisition and evaluation tech-
nologies”, Dessau, Germany, http://www.hziemann.de/
(accessed 22 Apr. 2004)
Mid Elbe Biosphere Reserve, 2003,
http://www.biosphaerenreservatmittlereelbe.de/frameset htm
(accessed 22 Apr. 2004)
Figure 1. Footprint of 4 DMC pan images projected into the
virtual image © Z/Imaging Imaging GmbH,
Germany, Copyright 2003
Explaining the difference between ,synchronous*
and ,syntopic* image acquisition. The synchronous
mode triggers all 4 separate cones at the same time.
The syntopic mode triggers them at an interval
defined by the flight velocity, about | msecond
apart. O Vexcel Imaging Austria, Copyright 2003
