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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004
Copy station
PC-unit Tape / disk box
Tapes/disks
Figure 6 Flight data storage connected to the copy station
There are possibilities for the future to include parts of the
post processing with the data copy process or to split up the
data of one photo flight mission into several projects, which
might be sent to different users.
The digital camera system offer a wide variety and flexibility
of image data handling to speed up projects, to reduce costs
and to improve quality.
Figure 7 DMC field data copy station
7. DATA POST PROCESSING
Digital aerial cameras are requiring Data Post Processing to
create the final output image from the raw data acquired
during the flight. There is a big difference for this post
processing between the different camera architectures like
line based and frame based sensors.
7.1 Line Sensor Cameras
For digital cameras based on line sensors the main challenge
is to correct the distortion of the individual lines, there is a
geometric shift between each line caused by the aircraft
movement. This correction requires precise information
about the external orientation of the sensor during the time of
exposure usually provided by an IMU Inertial Measurement
Unit. Before an user can start with the image post processing,
the GPS/IMU data post processing is necessary. Without this
data, the image post processing can not be done.
To achieve an acceptable post processing time, massive
computer infrastructure ( CPU farms ) is required. From an
economical point of view there is a high threshold for the
minimum workload to get a reasonable return of invest.
7.2 Frame Sensor Cameras
Frame sensor based cameras have a straight forward way for
the image data post processing by using standard
photogrammetric algorithms. Because of the stable X-Y
sensor geometry, GPS/IMU data are not required to create
the final output image. The post processing time is much
shorter comparing to line sensor cameras. The software is
running on standard workstations and is not requiring any
special computer infrastructure.
This is a huge benefit of the DMC, fast image data post
processing. With a standard high performance workstation
(e.g. dual 2.4 GHz XEON CPU with 1GB RAM ) the raw
image data can be processed, no special hardware, no special
environment and no special computer facilities are necessary.
All camera calibration data, geometric and radiometric
calibration, will be provided to the user on a CD. This data
will be used at the time of the image post processing.
With a minimum level of user interaction the software
automatically post processes the raw image data into the final
frame. The output format can be specified, multiple formats
like RGB and CIR can be created in parallel. Probably the
biggest advantage of the new digital aerial camera against
traditional film cameras is the immediate image access. It is
possible to get high resolution color imagery or color infrared
images within 24 hours after the photo flight.
8. REFERENCES
Hinz, A. (1999). The Z/I Imaging Digital Aerial Camera
System, Photogrammetric Week 1999, Eds D. Fritsch / R.
Spiller, Wichmann, Heidelberg pp 109 — 115
Heier H., Dórstel C., Hinz A. (2001). DMC - The Digital
Sensor technology of Z/I Imaging, Photogrammetric Week
2001, Eds D. Fritsch / R. Spiller, Wichmann, Heidelberg pp
93 — 103
Neumann, K. (2003) Aerial Mapping Cameras — digital
versus film The benefits of a new technology . Proceeding
from the ASPRS 2003 conference, May 5 -9 2003
