System assessment by image simulation requires synthetic scenarios that can be viewed by the device to be simulated. In
addition to physical modeling of the camera, a reliable modeling of scene elements is necessary. Software products for
modeling of target data in the IR should be capable of (i) predicting surface temperatures of scene elements over a long
period of time and (ii) computing sensor views of the scenario.
For such applications, FGAN-FOM acquired the software products RadTherm-IR (ThermoAnalytics Inc., Calumet,
USA) and IR-Workbench (OKTAL-SE, Toulouse, France). Inspection of the accuracy of simulation results by validation
is necessary before using these products for applications. In the first step of validation, the performance of both "thermal
solvers" was determined through comparison of the computed diurnal surface temperatures of a simple object with the
corresponding values from measurements. CUBI is a rather simple geometric object with well known material parameters
which makes it suitable for testing and validating object models in IR. It was used in this study as a test body. Comparison
of calculated and measured surface temperature values will be presented, together with the results from the
FGAN-FOM thermal object code F-TOM. In the second validation step, radiances of the simulated sensor views computed
by RadTherm-IR and IR-Workbench will be compared with radiances retrieved from the recorded sensor images
taken by the sensor that was simulated.
Strengths and weaknesses of the models RadTherm-IR, IR-Workbench and F-TOM will be discussed.
Within the scope of the investigation of material for camouflage, concealment, and deception (CC&D material) in
desert environment, it is necessary to evaluate the impact of turbulence on thermal imagers in the MWIR and in the
LWIR. Turbulence decreases the effectiveness of electro-optical systems. It causes a reduction of the spatial resolution
of thermal imagers, which is characterized by the turbulence modulation transfer function MTF. Turbulence MTF
depends on atmospheric parameters, e.g. the strength of atmospheric turbulence as described by the structure parameter
of the refractive index fluctuations, Cn2, the atmospheric path length, the cross-wind velocity, and on the sensor
parameters, i.e. the wavelength and the aperture diameter of the front optics. The total MTF is the product of turbulence
MTF and sensor MTF, which in turn is the product of detector MTF and optics MTF. As a figure of merit for the spatial
resolution, we used the area under the total MTF (MTFA). Based on our turbulence measurement that was taken in arid
climate in Negev desert, Middle East, we calculated the total MTFA for a dual-band thermal imager (MWIR and
LWIR) with two available optics under diverse turbulence conditions and for different path lengths up to 5 km. The
selected Cn2 values are representative for the diurnal run of Cn2 in arid summer or different times of day, respectively.
We defined a turbulence degradation factor X to estimate the impact of turbulence on the image quality as a function of
time of day and path length. Resulting MTFAs and the corresponding turbulence degradation factors will be discussed
CUBI is a rather simple geometrical object used in outdoor experiments with the objective of gathering data which can
be utilized in testing and validating object models in the thermal infrared. Since its introduction several years ago, CUBI
is gaining interest by an increasing number of research laboratories which are engaged in thermal infrared modelling.
Being a member of the worldwide CUBI Forum, the FGAN-FOM has installed a CUBI about 1 year ago. Since then,
CUBI surface temperatures are being recorded continuously, together with a set of associated environmental data. The
data collected are utilized to explore the capabilities of the FOM Thermal Object code F-TOM. For this purpose, the
model was modified to represent CUBI in model space. Likewise, the well-known IR signature prediction model
RadTherm/IR was applied to the CUBI problem. In this paper we will present CUBI and the philosophy behind it, the
comprehensive CUBI data collection effort at our place, and the development of the two different thermal models. Experimental
data and model predictions will be shown and compared. Strengths and weaknesses of the models will be
Optical imaging, including infrared imaging, generally has many important applications, both civilian and military. In recent years, technological advances have made multi- and hyperspectral imaging a viable technology in many demanding military application areas. The aim of the CEPA JP 8.10 program has been to evaluate the potential benefit of spectral imaging techniques in tactical military applications. This unclassified executive summary describes the activities in the program and outlines some of the results. More specific results are given in classified reports and presentations.
The JP 8.10 program started in March 2002 and ended in February 2005. The participating nations were France, Germany, Italy, Netherlands, Norway, Sweden and United-Kingdom, each with a contribution of 2 man-years per year. Essential objectives of the program were to:
1) analyze the available spectral information in the optronic landscape from visible to infrared;
2) analyze the operational utility of multi- and hyperspectral imaging for detection, recognition and identification of targets, including low-signature targets;
3) identify applications where spectral imaging can provide a strong gain in performance;
4) propose technical recommendations of future spectral imaging systems and critical components.
Finally, a stated objective of the JP 8.10 program is to "ensure the proper link with the image processing community".
The presentation is organized as follows. In a first step, the two trials (Pirrene and Kvarn) are presented including a summary of the acquired optical properties of the different landscape materials and of the spectral images. Then, a phenomenology study is conducted analyzing the spectral behavior of the optical properties, understanding the signal at the sensor and, by processing spectroradiometric measurements evaluating the potential to discriminate spectral signatures.
Cameo-Sim simulation software is presented including first validation results and the generation of spectral synthetic images. Results obtained on measured and synthetic images are shown and discussed with reference to two main classes of image processing tasks: anomaly detection and signature based target detection. Furthermore, preliminary works on band selection are also presented which aim to optimize the spectral configuration of an image sensor. Finally, the main conclusions of the WEAG program CEPA JP8.10 are given.
Theoretical and experimental work has been conducted to assess the feasability of the retrieval of target's emissivity and bi-directional reflectivity from broadband infrared imaging systems. Focus was on the [3-5micrometers ] band II region where very little information is available. For accurate handling of the measured at-sensor radiance, account must be taken of target-to-sensor air layer, even for short distances, particularly in band II where atmospheric CO2 has a strong absorption band around 4.26 micrometers . It is shown that full integral expression over the spectral bandwidth of the instrument must be used and that usual factorization of contributions due to target, atmosphere and radiometer may lead to large errors when inverting the signal for emissivity or bi-directional reflectivity. Although retrieval of band II target's emissivity is, as a rule, extremely difficult outdoor conditions for natural surfaces, this work demonstrates that a multi-temporal regression method gives very good results with attainable accuracy on emissivity within 2%. Estimate of retrieving errors due to necessary approximations made in the formulation of the signal has been made via simulations. Experimental verification based on actual data acquired in outdoor conditions is in progress.