Flocks of migratory birds are very often using geographic structures like rivers, valleys or coast lines for orientation.
Wherever the preferred migration routes are crossing the approach corridor of an airport there is an increased risk of bird
strike. Flocks of birds crossing the runway corridor of the new runway Northwest of the Frankfurt airport are kept under
surveillance now with in total three watch towers located at the river Main which in this case is the preferred used line of
orientation. Each of the watch towers carries an early warning system which consists of two pairs of stereoscopic thermal
imaging cameras sensitive in the mid wavelength infrared range (3 - 5 μm). A stereoscopic pair measures the swarm
size, direction of flight and velocity in real time and with high accuracy. From these results an early warning is derived
under all relevant weather conditions.
The fixed focus thermal imaging cameras are thermally compensated and designed for ultra low image distortion. Each
stereoscopic pair is aligned in the sub-pixel range and is controlled by a reference beam to ensure that the alignment is
preserved under all environmental conditions and over a very long time. The technical concept is discussed and the
design of the realized warning system at the Frankfurt airport is presented.
In case bird migration routes cross approach corridors near airports bird strike prevention with thermal imaging systems
has advantages compared to others technologies i.e. RADAR systems. In our case a stereoscopic thermal imaging system
sensitive in the mid wavelength range (3 - 5 μm) with high geometrical (640 × 512 pixel) and high thermal resolution (<
20 mK) measures in real time the swarm size, direction and velocity with high accuracy in order to give an early warning
under all relevant weather conditions during day, night and twilight. The system is self-calibrating to keep the relative
position of the paired stereoscopic thermal imagers in the sub-pixel range under all environmental conditions.
The stereoscopic systems are placed in a sufficient distance to the crossing with the take-off or landing path to enable
warning times of several minutes. Moreover the risk potential of the swarm is determined by taking the size of a single
bird as well as the number of birds in the swarm into account. By using this information an arrival time of the swarm at
the crossing point is determined and provided to the air security controllers together with the risk potential of the swarm.
A miniaturized near-field observation platform is presented comprising a sensitive daylight camera and an uncooled
micro-bolometer thermal imager each equipped with a wide angle lens. Both cameras are optimised for a range between
a few meters and 200 m. The platform features a stabilised line of sight and can therefore be used also on a vehicle when
it is in motion. The line of sight either can be directed manually or the platform can be used in a panoramic mode. The
video output is connected to a control panel where algorithms for moving target indication or tracking can be applied in
order to support the observer. The near-field platform also can be netted with the vehicle system and the signals can be
utilised, e.g. to designate a new target to the main periscope or the weapon sight.
Every year, numerous accidents happen on European roads due to bad visibility (fog, night, heavy rain). Similarly, the dramatic aviation accidents of year 2001 in Milan and Zurich have reminded us that aviation safety is equally affected by reduced visibility.
A dual-band thermal imager was developed in order to raise human situation awareness under conditions of reduced visibility especially in the automotive and aeronautical context but also for all transportation or surveillance tasks. The chosen wavelength bands are the Short Wave Infrared SWIR and the Long Wave Infrared LWIR band which are less obscured by reduced visibility conditions than the visible band. Furthermore, our field tests clearly show that the two
different spectral bands very often contain complementary information.
Pyramidal fusion is used to integrate complementary and redundant features of the multi-spectral images into a fused image which can be displayed on a monitor to provide more and better information for the driver or pilot.