Reconnaissance tasks and the detection of camouflaged targets can be improved if the different surface reflection conditions of natural and artificial surfaces can be discriminated in multispectral images. Analogue to the visible, colorimetry in the shortwave infrared spectral range has been presented in praxis and theory in . In this presentation we will discuss the influence of a four filter set onto the capability of the system to discriminate different spectral characteristics of two objects. An optimal choice of filters is presented in the sense of a homogenous discrimination characteristics across the SWIR band, taking into account the SWIR solar spectrum. Based on this choice two development issues were investigated: the accuracy of the color values with respect to measurement noise and the display of SWIR color images. As a figure of merit for color value accuracy the Noise Equivalent Wavelength Difference is introduced describing the minimum color difference that can be resolved/discriminated from the noise floor. Due to the lack of a physiologic counterpart as known from the visual colorimetry where the eye is used as reference for the three color channels, we will showcase a model for transforming and displaying SWIR colors in the R-G-B color space.
The typically used shortwave infrared spectral range (SWIR) between 900 nm and 1700 nm is a spectrally broader wavelengths range than the visible range. Available SWIR cameras generate a gray level image using the intensity over the entire spectral band. However, objects can exhibit completely different spectral behavior in this range. Plants have a high reflection at the lower end of the SWIR range and liquid water has a strong absorption band around 1400 nm, for example. We propose to divide the SWIR range into an appropriate number of spectral channels to extract more details from a captured image.
To extract this information the proposal follows a concept similar to color vision of the human eye. Analog to the three types of color receptors of the eye four spectral channels are defined for the SWIR. Each point of the image is attributed now by four “color values” instead of a single gray level.
For a comprehensive characterization of an object, a special SWIR colorimetry is possible by selecting appropriate filters with suitable band width and spectral overlap. The spectral sensitivity, the algorithms for calculating SWIR-color values, the discrimination of SWIR-color values by Noise Equivalent Wavelength Difference (NEWD) and spectral coded false color image display is discussed and first results with an existing SWIR camera are presented.
Modern reconnaissance strategies are based on gathering information using as many spectral bands as possible. Besides
the well-known atmospheric windows at VIS, MWIR and LWIR wavelength suitable for long range observation progress
in detector technology has provided excess also to the atmospheric window from 1.0 to 1.7 μm known as SWIR.
Independent of the chosen spectral band all applications are longing to achieve the largest observation range possible.
Thus, a concept for comparing the sensors in different wavelength bands is appreciated.
Achievable ranges are influenced in part by the atmospheric conditions and in part by the capability of the imaging
sensor, only the latter are under the control of the instrument manufacturer. In range simulation the contribution of the
sensor can be efficiently characterized by using the MRC and the MRTD concept. The minimal resolvable contrast
(MRC) as a function of spatial frequency is a decisive figure if merit for the VIS and SWIR. The minimum resolvable
temperature difference (MRTD) as a function of spatial frequency is the same for MWIR and LWIR.
All relevant sensor data are covered by MRC and MRTD, respectively, and thus can be introduced into range calculation
by simply measuring the MRC or MRTD data curves.
Based on measured MRC data range calculations for three imaging sensors (VIS, NIR and SWIR) are presented for
selected atmospheric conditions together with significant captured images.
Cameras for the SWIR wavelength range are becoming more and more important because of the better observation range for day-light operation under adverse weather conditions (haze, fog, rain). In order to choose the best suitable SWIR camera or to qualify a camera for a given application, characterization of the camera by means of the Minimum Resolvable Contrast MRC concept is favorable as the MRC comprises all relevant properties of the instrument. With the MRC known for a given camera device the achievable observation range can be calculated for every combination of target size, illumination level or weather conditions. MRC measurements in the SWIR wavelength band can be performed widely along the guidelines of the MRC measurements of a visual camera. Typically measurements are performed with a set of resolution targets (e.g. USAF 1951 target) manufactured with different contrast values from 50% down to less than 1%. For a given illumination level the achievable spatial resolution is then measured for each target. The resulting curve is showing the minimum contrast that is necessary to resolve the structure of a target as a function of spatial frequency. To perform MRC measurements for SWIR cameras at first the irradiation parameters have to be given in radiometric instead of photometric units which are limited in their use to the visible range. In order to do so, SWIR illumination levels for typical daylight and twilight conditions have to be defined. At second, a radiation source is necessary with appropriate emission in the SWIR range (e.g. incandescent lamp) and the irradiance has to be measured in W/m2 instead of Lux = Lumen/m2. At third, the contrast values of the targets have to be calibrated newly for the SWIR range because they typically differ from the values determined for the visual range. Measured MRC values of three cameras are compared to the specified performance data of the devices and the results of a multi-band in-house designed Vis-SWIR camera system are discussed.
The video output of thermal imagers stayed constant over almost two decades. When the famous Common Modules were employed a thermal image at first was presented to the observer in the eye piece only. In the early 1990s TV cameras were attached and the standard output was CCIR. In the civil camera market output standards changed to digital formats a decade ago with digital video streaming being nowadays state-of-the-art.
The reasons why the output technique in the thermal world stayed unchanged over such a long time are: the very conservative view of the military community, long planning and turn-around times of programs and a slower growth of pixel number of TIs in comparison to consumer cameras. With megapixel detectors the CCIR output format is not sufficient any longer. The paper discusses the state-of-the-art compression and streaming solutions for TIs.
The thermal imager ATTICA was designed to fit into the thermal sights of the new German Infantry tank PUMA. The
flexible approach for the optical concept, using different folding mirrors allows meeting the different available space
requirements for thermal sights also of other tanks like the main battle tank Leopard 2 and the infantry fighting vehicle
Marder. These tanks are going to be upgraded. The flexible concepts of the thermal imager optics as well as the
mechanical packing solutions for the different space volumes of the commander and gunner sights of the vehicles are
The new PUMA tank is equipped with a fully stabilized 360° periscope. The thermal imager in the periscope is identical
to the imager in the gunner sight. All optronic images of the cameras can be fed on every electronic display within the
tank. The thermal imagers operate with a long wave 384x288 MCT starring focal plane array. The high quantum
efficiency of MCT provides low NETD values at short integration times. The thermal imager has an image resolution of
768x576 pixels by means of a micro scanner. The MCT detector operates at high temperatures above 75K with high
stability in noise and correctibility and offers high reliability (MTTF) values for the complete camera in a very compact
design. The paper discusses the principle and functionality of the optronic combination of direct view optical channel,
thermal imager and visible camera and discusses in detail the performances of the subcomponents with respect to
demands for new tank applications.
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.
The development of an integrated sensor device BiSAM (Biological Sampling and Analysing Module) is presented which is designed for rapid detection of aerosol or dust particles potentially loaded with biological warfare agents. All functional steps from aerosol collection via immuno analysis to display of results are fully automated.
The core component of the sensor device is an ultra sensitive rapid analyser PBA (Portable Benchtop Analyser) based on a 3 dimensional immuno filtration column of large internal area, Poly HRP marker technology and kinetic optical detection. High sensitivity despite of the short measuring time, high chemical stability of the micro column and robustness against interferents make the PBA an ideal tool for fielded sensor devices. It is especially favourable to combine the PBA with a bio collector because virtually no sample preparation is necessary.
Overall, the BiSAM device is capable to detect and identify living micro organisms (bacteria, spores, viruses) as well as toxins in a measuring cycle of typically half an hour duration. In each batch up to 12 different tests can be run in parallel together with positive and negative controls to keep the false alarm rate low.
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.