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Close-range imaging, long-range vision

Ralf Jantos', Thomas Luhmann‘, Jürgen Peipe”, Carl-Thomas Schneider”
! University of Applied Sciences, Institute for Applied Photogrammetry and Geoinformatics,
Ofener Str. 16, D-26121 Oldenburg, Germany - (luhmann, tecklenburg)@fh-oldenburg.de
? University of Armed Forces Munich, Institute for Photogrammetry and Cartography,
D-85577 Neubiberg, Germany - j-k.peipe(gUniBw-Muenchen.de
? AICON 3D Systems, Celler Str. 32, D-38114 Braunschweig, Germany — ct.schneider@aicon.de
Commission V, WG V/1
KEY WORDS: Close range photogrammetry, Bundle adjustment, Calibration, Accuracy, Image quality, Color processing
Digital camera backs to be connected with analogue photographic cameras have been developed for professional studio photography
in addition to the conventional film-based procedure. The acquired high resolution digital images can be suitable for
photogrammetric purposes too. Recently, the Kodak DCS Pro Back providing 4k x 4k pixel was introduced. The paper describes first
results of the geometric and radiometric performance evaluation of the digital back adapted to a Mamiya 645 medium format camera
High resolution area array CCD cameras enable high precision
photogrammetric object reconstruction required for a number of
close range photogrammetry applications, especially in
industry. For this, still cameras such as Kodak DCS 460, 660,
760 providing 3000 x 2000 pixel have been widely and
successfully used. In addition, several manufacturers have been
offering digital camera backs to be connected with small,
medium or large format analogue photographic cameras (Peipe,
1995). They allow for an interchange between film and digital
data acquisition. All the existing equipment and accessories of
analogue cameras can be utilised. These camera backs have
been primarily developed for professional studio photography,
but are of interest for photogrammetric tasks too.
In 1996, the first 4000 x 4000 pixel camera back was
introduced by the Dicomed company. Photogrammetric test
measurements using the Dicomed BigShot connected to a
Hasselblad camera body resulted in insufficient accuracy
measures due to various stability problems (Peipe, 1997). Based
on the Dicomed back, Rollei tried to design the Rollei Q16 as
digital metric camera (Godding, 1998), but the attempt failed.
At the Photokina 2000, Kodak launched the DCS Pro Back, a
4k x 4k single shot camera back compatible with Hasselblad
555 ELD and Mamiya RZ 67 (Schneider et al. (2002) present
first photogrammetric investigations). Unlike other digital
backs, the images can be taken untethered to a PC and stored on
two 1 GB IBM Microdrives. Meanwhile, Kodak introduced
new versions of the DCS Pro Back that enlarge the range of
medium and large format cameras which the digital back can
adapted to (Kodak, 2002), lately the DCS Pro Back 645M (for
Mamiya 645) and 645C (for Contax 645).
In this paper, the performance of the Kodak DCS Pro Back is
evaluated by laboratory measurements including investigations
into the sensor quality and the determination of the accuracy of
photogrammetric 3-D object reconstruction achieved by
connecting the back with a "small" medium format Mamiya
645 camera body (45 mm x 60 mm image format).
The handheld, lightweight (0.77 kg) portable (with on-board
batteries) DCS Pro Back features a Kodak 16 megapixel sensor
(4096 x 4096 pixel) measuring 36.7 mm x 36.7 mm. The pixel
size amounts to 9 pm x 9 um. About every 1.6 - 2 seconds an
image can be acquired - at ISO 100 to 400. The color LCD
allows an immediate image quality check. A removable IR
filter protects the images from infrared light. From a single shot
a 36-bit image (12 bits per color) can be generated resulting in
96 MB raw RGB data, compressed to image files of 12-22 MB.

Fig. 1: Kodak DCS Pro Back 645M

Fig. 2: Camera in use
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