International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
ru
Figure 6: DigiCam-K14 with LiteMapper system
installation (© IGI 2004).
GPS/inertial system. The camera is rigidly fixed on one
common platform with the LiteMapper laser scanner and the
AEROcontrol-IId for providing the direct georeferencing data
for laser scanner and camera in parallel. The high performance
of the AEROcontrol-IId was already proven several times and
could be seen for example from Cramer (2003) The
LiteMapper system was officially presented during the last
Photogrammetric Week 2003 in Stuttgart/Germany. Details on
the system parameters are given at www.igi-systems.com
(2004). The airborne system installation is depicted in Figure 6.
The modified DCS Pro 14n is fixed in the dark box in the right.
In order to adjust the field of view of camera and laser the
camera is mounted in that way that the small sensor side is
pointing across flight direction, which also has advantages for
photogrammetric point determination since larger base lengths
are possible. On top of the LiteMapper laser scanner the IMU-
IId is clearly visible. Within this specific system installation, all
components were mounted on a non-stabilized platform fixed to
the aircraft body via spiral springs for passive damping of
aircraft vibrations.
Although the modified Kodak DCS Pro 14n as sub-part of the
laser scanner platform is originally not designed for
photogrammetric point determination a test was done by
Institute for Photogrammetry (ifp) in mid of April 2004, where
the whole system was flown in the photogrammetric test area
Vaihingen/Enz (close to Stuttgart/Germany) in order to estimate
the photogrammetric performance of the camera in combination
with self-calibration techniques. Besides the large number of
signalised ground control points special resolution targets are
provided within the test area to evaluate the geometric and
radiometric resolution of the sensor. During the mission two
different image blocks using 28mm optics with standard
overlaps were flown at 700m (8 flight lines east-west with 21
images each) and 400m above ground (4 flight lines north-south
with 8 images each) resulting in image scales of 1:25000 and
1:15000 respectively. The corresponding ground sample
distances are 20cm and 12cm.
During the time of writing only very first results are available
for the Vaihingen/Enz test showing an accuracy in the range of
| pixel which is very sufficient for this initial evaluation. A
detailed analysis of test flight results including the topics like
in flight camera calibration and image resolution will be given
during the conference.
5. SUMMARY
As it could be shown in the paper, medium format digital
sensors have their right to exist and could be used in several
applications. The big advantages of such airborne sensors are
their high flexibility and relatively low costs of operation. If
certain photogrammetric pre-necessities are fulfilled (i.e. stable
interior camera geometry as most important fact and the
requirements already mentioned in Section 3) these sensors can
even be used for photogrammetric point determination and
stereo processing. Nonetheless, their main application wiil be in
the field of photointerpretation and fast orthoimage generation
based on existing DTM for smaller areas. Application tasks are
monitoring of land use changes, disaster and risk assessment,
forestry and others like real estate search and promotion or
tourism. Certainly, such medium format systems will not
replace the professional large format digital cameras, which are
inevitable for highest photogrammetric demands and large area
projects, but they might be of increasing interest for such
groups of users, which are more interested in multispectral
analysis and interpretation of more locally oriented projects.
From this future application a closer look on the radiometric
quality of those sensor systems seems to be necessary and will
be done. Especially the FOVEON X3 (FOVEON 2004)
technology seems to be an alternative to supplement the
inherent need for colour interpolation when using traditional
Bayer pattern.
ACKNOWLEDGMENTS
The author would like to thank Ernesto Cortés, GeoSistemas
Aéreos (GeoSisA) for sharing his expertise and experiences
from true operational point of view. IGI provided the data for
the Vaihingen/Enz test flight. Their continuous support, namely
Jens Kremer and Michael Müller, is gratefully acknowledged.
REFERENCES
Blanc, N. (2001): CCD versus CMOS — has CCD imaging come
to an end?, in Fritsch/Spiller (eds.) Photogrammetric Week '01,
Wichmann Verlag, Heidelberg, pp. 131-137.
Cramer, M. (2003) Erfahrungen mit der
Georeferenzierung, PFG 2003(4), pp. 267-278.
DIMAC (2004): http://www. dimacsystems.com (accessed April
2004).
FOVEON
2004).
Gorin B., Matthews, B. & Threadgould, A. (2002): An ultra
high resolution, electro-optical framing camera with a 9216 by
9216 focal plane array and differential image motion
compensation, in Proceedings ASPRS annual congress, April
19-26, 2002, Washington, available on CD, 12 pages.
Kraus, K. (1990): Photogrammetrie, Dümmler Verlag, Bonn,
Germany, 334 pages.
Mostafa, M. (2003): Design and performance of the DSS, in
Fritsch/Spiller (eds.) Photogrammetric Week '03, Wichmann
Verlag, Heidelberg, pp. 77-88.
Petrie, G. (2003): Airborne digital frame cameras,
Geolnformatics 7(6), October/November 2003, pp. 18-27.
Petrie, G. (2004): Personal correspondence.
direkten
(2004): http://Www.foveon.com (accessed April
