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a frame size of 4k by 2.7 k pixels for red, green, blue and near
infrared [Leberl 2003].
Fig. 1: ULTRACAMp Sensor Unit (SU) and
Storage/ComputingUnit (SCU)
2.1 Design issues
ULTRACAMp was designed to replace the analog film camera.
This concept leads to specific design issues, among them the
image format, the frame rate and quality parameters of the
digital output of the camera.
The size of the image across track is related to the number of
flight lines one needs to cover a distinct project area at a
specific image scale. We have assembled evidence that 11,500
pixels across the swath will outperform aerial film with its
swath width of 23 cm. Therefore, the CCD pixel to improve on
scanned film will be at an equivalent spacing of 20 jim (201m
x 11,500 pixels = 230 mm). This perhaps surprises, but is
supported by superior image quality.
The image format along track has its major influence on the
ability of the camera in taking stereoscopic image sequences.
ULTRACAMp offers 7500 pixels, which is a perfect trade off
between image data quantity and stereoscopic quality. Together
with its focal length of 100 mm and a frame rate of better than
I frame per second ULTRACAMp is well prepared to be
assigned to nearly every kind of photo mission.
2.1.1 Advantages of going digital
The transition from film based aerial cameras to digital sensors
closes the last gap in the all digital photogrammetric
production line. Not without good reasons we expect
advantages from the digital camera. Some of them are obvious.
e Radiometry: Digital images have superior radiometry and
no grain. This provides better matching accuracy, better
stereo, resolution in dark shadows and more success in
automated procedures. The high dynamic range of more
than 12 bit as being offered by ULTRACAMp allows
more flying days in marginal weather or under low light
conditions.
e Geometry: A superior geometric performance is based on
the rigidity of the camera backplane and the fact, that the
sensor needs not to be removed from the camera as it is
the case at film based photography.
e Work Flow: The end-to-end digital work flow offers
numerous advantages. The contributions of the digital
camera are in flight quality control and instant availability
of the image data without any film processing and
scanning.
e High frame rate at no additional costs: Photo missions
without costs for film opens the door to new approaches.
The transition from the 60 % forward overlap to a 80 % or
even 90 % overlap offers better aerial triangulation
results, a reduction of occlusions and a significant
enhancement in robustness.
e Multi-spectral imaging: ULTRACAM), produces a set of
high resolution panchromatic, true colour and false colour
infrared images simultaneously. This goes far beyond
what film can do and offers a new kind of
photogrammetric application.
2.0 ULTRACAM | Product Configuration
ULTRACAM| consist of four main components, namely the
Sensor Unit (SU), the Storage and Computing Unit (SCU), the
Interface Panel (IP) and the Mobile Storage Unit (MSU).
2.2.1 Sensor Unit
The heard of the system is the SensorUnit (SU) with ıts 13
area CCD sensors. A distributed parallel sensing concept offers
the fast frame grabbing of almost 90 MegaPixel images at one
second.
2.2.2 Storage/Computing Unit
The Storage/Computing Unit (SCU) is equipped with a set of
15 small size computers in such way, that each CCD module of
the Sensor Unit is accompanied by a separate "private" storage
and computing component with a capacity of dual redundant
storage of up to 2692 images. The 15 computers (one serves as
the controller, one is redundant) can be used to go for a fast
post processing of the raw image data.
2.2.3 Interface Panel
The Interface Panel (IP) offers a well designed intuitive
graphical user-interface which guides the interaction with the
camera system during the photo mission and on the ground.
The inflight control of the camera as well as the post-
processing of the image data is managed trough the IP.
2.2.4 Mobile Storage Unit
The Mobile Storage Unit (MSU) serves as the image tank for
off loading and data transport whenever the SCU needs 10 be
cleared. This offers a huge amount of flexibility and fast data
transfer from the aircraft to the office. A dump of a full set of
2692 images from the SCU to the MSU can be performed
within about one hour.
3. CCNS / AEROCONTROL
The CCNS is a GPS and aircraft. directional gyro based
guidance, positioning and sensor management system for aerial
survey flight missions. The basic system consists of the Central
Computer Unit (CCU), at least one Command and Display
Unit (CDU) and the mission planning software package
WinMP. The system can operate two airborne sensors of any
