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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
connected to the DMC during the photo
flight mission. The postprocessing software
can produce several different types of output
files from the set of raw images stored on the
FDS. Full-resolution panchromatic image
files are produced from images taken by the
camera's four panchromatic sensors. Also,
colour and colour-infrared output images can
be produced using the full-resolution
panchromatic imagery combined with the
Nay
SPS
i ASMS
Red Time Cort [
DMC | Red Time Consoles fRTC]
Video
Camera
ASMS (software)
data from the multispectral sensors. This
allows the possibility of producing four types
as ue || Toughbook Sensor
1
i
|
|
: t Management System
With Touch Screen |
Display (optional):
of full resolution images (7680 x 13824):
panchromatic, colour, near-infrared, and 4-
band. Files matching the resolution of the
T-AS | (user supptod)
— TE colour and near-infrared (multispectral)
arbome pone it sensors can also be produced (2048 x 3072).
ground based | -[ buc Pestprecessiny System (software) These images can be produced as colour,
{ | colour-infrared, 4-band, and near-infrared. A
: DMC-Data Server 20MC Imagary colour file is defined as a file consisting of
ISMP (cover Need i ERR a Systems only the red, green, and blue colour bands.
vison Perv Jones T ed | With 24 disks Colour-infrared is defined as a file consisting
Mission Reporting v ——À of near-infrared, red, and green bands. 4-
ieu FDS Disks or band files contain all bands, in the order red,
CopyStation green, blue, and near-infrared.
Uninterruptable
Power Supply (UP £i Postprocessing is completed in two steps:
radiometric processing and then geometric
Figure |. DMC system components
Ideally, one individual large-area CCD chip similar to the
information contents of existing film formats would be the
perfect geometric solution for an aerial image acquisition
system. However, since the size of commercially available
imaging sensors is limited, it is not possible to choose the ideal
solution for the focal plane of an airborne digital camera to
fulfil the normal photogrammetric requirements. The DMC,
therefore, overcomes this limitation by parallel operation of
several compact camera heads directed at the scene under
slightly oblique field angles (Heier, et al, 2002).
The DMC consists of eight sensors: four panchromatic sensors
and four multispectral sensors. The multispectral sensors are 3k
x 2k in size, with one sensor capturing red data, one capturing
blue data, one capturing green data, and one capturing near-
infrared data. The four panchromatic sensors (Figure 2) cach
capture one image of a particular area (7k x 4k), which partly
overlap one another. The four images are captured from slightly
different positions and synchronous in time to about 0.01 msec.
They are subsequently used to produce one large image
composite, 7680 x 13824 in size as shown in Figure 2. Figure 3
shows the DMC installed on a Z/I gyro stabilized mount. From
the image data captured by the DMC, one can produce a variety
of output types using the postprocessing software.
The image data that the camera captures is stored on the three
Flight Data Storage (FDS) units, which are connected to the
camera during the flight. The total FDS disk space is large
enough to hold data that will produce 2200 final output images.
The FDS system has three individual, removable storage
modules that are transferred to the ground-based postprocessing
station. Table 1 shows the complete workflow including flight
project planning and image data capturing.
The DMC postprocessing software is used for producing output
images from the raw image data that is stored on the FDS
397
processing.
Figure 2.
Footprint of 4 pan
images projected
into the virtual
image (yellow
area)
Figure 3. Left: Lens cone with panchromatic camera head
Right: DMC with gyro stabilized mount
Radiometric processing compensates for the effects of
temperature, aperture, and other radiometric factors (Diener et
al. 2000; Heier 2001). The intermediate images, generated from
radiometric processing, are written to the intermediate RAID
storage on the postprocessing server. The intermediate images
