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IENTS
d by Grants in Aid for
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
LOW-COST OPTICAL CAMERA SYSTEM
FOR DISASTER MONITORING
F. Kurz, O. Meynberg, D. Rosenbaum, S. Türmer, P. Reinartz, M. Schroeder
German Aerospace Center, 82234 Wessling, Germany - (franz.kurz, oliver.meynberg, dominik.rosenbaum,
sebastian.tuermer, peter.reinartz, manfred.schroeder)@dir.de
Commission VIII, WG 1
KEY WORDS: Hazards, Aerial optical camera, Real-time, Performance, Thematic processing, Cost
ABSTRACT:
Real-time monitoring of natural disasters, mass events, and large accidents with airborne optical sensors is an ongoing topic in
research and development. Airborne monitoring is used as a complemental data source with the advantage of flexible data
acquisition and higher spatial resolution compared to optical satellite data. In cases of disasters or mass events, optical high
resolution image data received directly after acquisition are highly welcomed by security related organizations like police and rescue
forces. Low-cost optical camera systems are suitable for real-time applications as the accuracy requirements can be lowered in return
for faster processing times. In this paper, the performance of low-cost camera systems for real-time mapping applications is
exemplarily evaluated based on already existing sensor systems operated at German Aerospace Center (DLR). Focus lies next to the
geometrical and radiometric performance on the real time processing chain which includes image processors, thematic processors for
automatic traffic extraction and automatic person tracking, data downlink to the ground station, and further processing and
distribution on the ground. Finally, a concept for a national airborne rapid mapping service based on the low-cost hardware is
proposed.
1. INTRODUCTION
With the rise of new airborne platforms in particular of UAVs
there is an increasing demand for low-cost, low-weight and
small optical camera systems. These aspects become even more
important as the payload of these flying platforms is limited and
end users such as police and rescue forces want to equip their
proprietary flight squadrons at limited costs.
Also, the possibility of real-time processing of airborne optical
camera images in combination with high frame rates paves the
way for innovative applications. It is possible to monitor highly
dynamic processes like traffic (Rosenbaum, 2008, Leitloff,
2010) or persons (Sirmacek, 2011). DSMs (Digital Surface
Models) generated in real time (Zhu, 2010) and real-time
orthophoto maps are a valuable data source in different
Scenarios.
Thus, combining the new airborne platforms and real-time
processing capabilities, new applications in the context of
disaster monitoring are emerging.
There are three low-cost, real-time optical sensor units operated
at DLR, the 3K and 3K+ camera system licensed for the DLR
airplanes Cessna and Do228 as well as a sensor unit called
CHICAGO integrated in a motorized DLR glider powered by a
hydrogen-oxygen fuel cell (Coppinger, 2010). For all sensors,
the real-time processing chain is installed aboard the aircraft,
i.e. data can be processed directly after the acquisition and sent
down to a ground station. A real-time georeferencing processor
is implemented followed by thematic processors for automatic
traffic detection and automatic person tracking. All hardware
components are relatively cheap, except for the GPS/Inertial
system from IGI (IGI, 2011). Thus, efforts are made to replace
the IMU by a software solution e.g. by optical navigation
(Kozempel, 2009), but in the proposed processing chain the
GPS/IMU remains included to allow real-time processing.
In chapter 2, a short overview over the hardware and software
system is given, followed by the evaluation of the system
33
performance in chapter 3 in terms of processing time and
quality parameters of the processors.
Chapter 4 describes the concept as well as the investment costs
and operational costs for an airborne German wide rapid
mapping service. Finally, the pros and cons of the proposed
airborne monitoring service are discussed in the context of
natural disasters.
2. SYSTEM OVERVIEW
2.1 Hardware
The system components used for the real time processing chain
from the airplane to the ground station are described in (Kurz,
2012). In the following a short summary is given. Each of the
3K/3K+/CHICAGO systems consists of three non-metric Canon
cameras (Fig. 1). For the 3K system the Canon EOS 1Ds Mark
II camera with Canon lenses is used, whereas the successor
models 3K+/CHICAGO use the CANON EOS 1Ds Mark III
camera with Zeiss lenses. The nominal focal length for 3K/3K+
is 50 mm and for the CHICAGO system 35 mm in the side-look
and 50mm in forward / backward direction. The 3K and 3K+
systems are mounted on a ZEISS aerial shock mount ready for
the DLR airplanes. The main differences between 3K and
3K+/CHICAGO are the cameras and lenses, the rest of the
software components remain the same. The Mark III camera
delivers 21.0 MPix compared to 16.7MPix of the Mark II
camera. Thus, the ground sample distance (GSD) of an image
taken from 1000 m above ground level (AGL) in nadir direction
is 15 cm and 13 cm for the 3K and the 3K- systems,
respectively.
The on-board system consists of the optical sensors, the
GPS/Inertial system, the processing units, and a C-band
microwave data link with a downlink capacity of up to 54
MBit/s depending on the distance and bandwidth (Figure 2).
