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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part BS. Istanbul 2004
4.2 KODAK DCS Pro 14n system
The second camera system being introduced in more details
within this paper is the already mentioned Kodak DCS Pro 14n,
which is a camera system available on market since June 2003.
In contrary to most other digital cameras this camera model uses
a CMOS sensor. From Blanc (2001) the performance of todays
CMOS active pixel sensors is close or even better than their
CCD equivalents. Just recently (March 2004) a slightly
modified version, the Kodak DCS Pro SLR/n was made
available, where the ISO range was upgraded compared to the
predecessor model DCS Pro 14n. Nonetheless, version updating
is possible by replacing the CMOS matrix sensor and the
analogue electronics part. The main technical specs of the DCS
Pro 14n are given in Table 1. More detailed technical
specifications can be seen from the manufacturers WWW site at
www.kodak.com (2004).
Besides the discussed topics of base-to-height ratio and image
motion effects, the maximum feasible image frame rate is of
concern for use of digital sensors in airborne environment. In
this case the DCS Pro 14n allows for the internal buffering of
approx. 20 full resolution images with an maximum image
recording rate of 1.7 frames / sec as given in the specification
sheets. If the image data are stored external (CompactFlash card
or computer hard disc) the maximum frame rate is highly
dependent on the used hardware. Dependent on the available
equipment frame rates from 0.6 - 5 sec / frame are documented.
Since now, only few of those cameras are tested in airborne
photogrammetric environments. To the authors knowledge tests
were already done from IGI Germany (with a modified version
of DCS Pro 14n), the Mexican photogrammetric company
GeoSistemas Aereos (GeoSisA) and GeoTechnologies
consultancy at Bath Spa University College (Petrie 2004).
Experiences from the first two system installations are covered
in more details in the following.
DCS Pro 14n at GeoSistemas Aéreos (GeoSisA) The Mexican
flight company GeoSistemas Aércos (GeoSisA) is using the
Kodak DCS Pro 14n since September 2003 mainly for
production of large area coloured orthoimage mosaics. Since
that time different projects with several thousand sqkm are
already flown. As an example a production project to survey for
clandestine garbage dumps in three of the biggest municipalities
in Mexico (Tijuana, Rosarito and Puerto Penasco) should be
mentioned. The Tijuana-Rosarito block covered an area of
65km by 40km with 21 lines (60% forward overlap and 30%
sidelap) and 75 to 50 photographs per line (as function of the
longitude) making a total of 1057 exposures for the complete
block. The blocks were flown at an average of almost 4000m
above ground, with some variations dependent on differences in
terrain height. At this flight level, each photograph covered
almost 4000m wide and 3000m forward. Based on the used AF
Nikkor 35mm f/2D lens the obtained image scale is 1:110000.
The flight was designed in order to obtain a ground sample
distance (GSD) of 80cm, but in high contrast areas spatial
resolution was higher. In order to keep the use of the system as
flexible as possible an outside platform was designed, which
can be placed outside any available airplane and command from
the inside of the aircrafts cabin in order to be able to control tilt,
bank, and drift angle to maintain the camera levelled and
aligned. This installation is shown in Figure 5. The reliability of
the system in this operational mission was very high. The whole
job was done in less than 6 days. Using the base information
data from Mexican mapping agency (i.e. topographic map
1:50000, existing small scale orthomosaic map 1:75000 and
775
CMOS 13.89 million total pixel (4560 x 3048 pix)
sensor 13.50 million recorded pixel (4500 x 3000
pix)
Format 36 mm x 24 mm (full format), no focal length
size magnification
Sensitivity | Pro 14n ISO 80 — 400 (full resolution)
Pro SLR/n ISO 6 — 1600
Bit depth | 12 bit / colour
Frame rate | Burst rate 1.7 frames / s
Burst depth ~20 frames (full res., 512 Mb
RAM)
Table 1: Kodak DCS Pro 14n technical specifications.
i
Figure 5: DCS Pro 14n in outside platform installation
(O GeoSisA 2004).
DTM) an accuracy of 8m is obtained from AT. This accuracy is
in the range of several pixels only, caused by the lower quality
of input data used for orientation, but fully agrees with the
required accuracy demands. From another project with 60cm
GSD (flying height 3000m) an orthomosaic accuracy of 2m
(RMS) was proven based on check point data from 1:1000 base
map and field topography.
From their practical experiences with digital medium format
images obtained from Kodak DCS Pro 14n GeoSisA proved
that the coloured mosaics have more semantic information and
resolution than high-resolution satellite imagery (i.e. Ikonos and
Quick Bird). The mosaics are delivered to the clients in less
time than the satellite image (even when the satellite image has
been already taken) and less expensive, especially when the
clients need is to cover an area considerably less than the
minimum size image offered by the satellite provider. Besides
that the stereo capability of digital airborne images supports the
clients within the photointerpretation process. Working stereo is
possible from satellite images also, but considerably more
expensive since an additional scene is necessary.
4.3 IGI diGlcam-K14 system
The new dIGlcam series sensor systems of IGI has been
combined with the IGI LiteMapper (LiDAR Terrain Mapping
System) as imaging sub-component of an airborne laser
scanning platform. The dIGIcam-K14 is based on the Kodak
DCS Pro 14n and has been improved for airborne operations
with a proprietary external housing and fixed focus lens. Also,
the dIGlcam benefits of the fully integration to the IGI CCNS
guidance and sensor management and AEROcontrol integrated