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, C-n(2), 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 and 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 C-n(2) values are representative for the diurnal run of C-n(2) in and 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 V time of day and path length. Resulting MTFAs and the corresponding turbulence degradation factors will be discussed in details.

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 discussed.

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:analyze the available spectral information in the optronic landscape from visible to infrared;analyze the operational utility of multi- and hyperspectral imaging for detection, recognition and identification of targets, including low-signature targets;identify applications where spectral imaging can provide a strong gain in performance;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.

An experimental study to address issues encountered in the determination of surface bi-directional reflectivity and emissivity of materials [3-5microm] region has been conducted in outdoors conditions. The measurement protocol included radiometric infrared camera acquisitions in both [3-5microm] (band-2) and [8-14microm] (band-3). The band-2 bi-directional reflectivity is obtained from a sequence of sunlit and shade measurements. Best results are found with measurements relative to a diffuse aluminum reflector. Direct inversion of band-2 radiometric signal is unstable. A multitemporal method is introduced and the slope of the linear regression is the searched emisssivity. A detailed analysis is conducted to assess the impact of different sources of systematic errors. The proposed method is found to have a good potential with an estimated measurement error in the range of 2%.

Theoretical and experimental work has been conducted to assess the feasibility of the retrieval of target's emissivity and bidirectional reflectivity from broadband infrared imaging systems. Focus was on the [3-5mum] 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 4.26mum. 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 IT 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.

Black soap films from aqueous solutions of sodium dodecyl sulphate are studied by micro-Raman confocal spectroscopy. At the end of the draining process films of different thicknesses are obtained depending on the experimental conditions: Working in a closed humidified chamber leads to common black films while, under evaporation or in the presence of electrolyte, Newton black films are observed. From the Raman spectra of these films, quantitative information is deduced about the conformational and lateral order of the aliphatic surfactant chains, as well as the thickness of the residual water layer. More accurate measurements of the thickness of these ultimate films have been carried out by transmission ellipsometry and their effective refractive index measured by Brewster angle reflectivity. The thinner films present higher molecular organization and their aqueous core exhibits unusual spectral features.

RESUME - Ce travail aborde les problèmes de la radiométrie IR dans la bande (3- 5 µm) conjuguée à la bande (8-13µm) et des méthodes permettant de remonter aux propriétés thermo-optiques des fonds terrestres (émissivité, réflectivité bidirectionnelle). En plus de la difficulté théorique due au caractère « mal posé » du problème, la définition, même des grandeurs et la manipulation précise des quantités radiométriques induisent de très sérieuses difficultés , notamment si les instruments sont à bandes larges. Une simple inversion des relations radiométriques a peu de chance de conduire à des résultats précis, mais peut donner un ordre de grandeur. Des méthodes plus élaborées utilisant des contraintes est une voie qu'il apparaît nécessaire d'explorer. ABSTRACT- This work aims at addressing problems in IR band (3-5 µm) together with band (8-14 µm)and in methods allowing for retrieval of radiative properties (emissivity, bidirectional reflectivity) of terrestrial surfaces. Beside the theoretical difficulty of this "ill-defined" type of problem, the very definition of variables and accurate usage of radiometric quantities induce severe difficulties, particularly in case of broad band instruments. Simple inversion of radiometric equations is highly unstable and cannot give but at best a rough estimate. More sophisticated methods based in constraints imposed to the system's variables represent a way that is worth exploring.