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.
When designing camouflage it is important to understand how the human visual system processes the information to discriminate the target from the background scene. A vision model has been developed to compare two images and detect differences in local contrast in each spatial frequency channel. Observer experiments are being undertaken to validate this vision model so that the model can be used to quantify the relative significance of different factors affecting target conspicuity. Synthetic imagery can be used to design improved camouflage systems. The vision model is being used to compare different synthetic images to understand what features in the image are important to reproduce accurately and to identify the optimum way to render synthetic imagery for camouflage effectiveness assessment. This paper will describe the vision model and summarise the results obtained from the initial validation tests. The paper will also show how the model is being used to compare different synthetic images and discuss future work plans.
For a variety of training and simulation purposes even photo-realistic synthetic imagery is inadequate because of the impact of subtle effects on the eye and on other sensors. It is essential that the synthetic imagery is a physically accurate representation of the real-world and captures all the inherent variability of different backgrounds. CAMEO-SIM has been developed to meet these requirements. Recent work has improved the atmospheric modelling and thermal shadow simulation. In addition, novel concepts to introduce the three-dimensional spatial and spectral variability required are under consideration. It is essential that the fidelity of the imagery generated is evaluated, to ensure that it is 'fit for purpose'. Therefore a toolset, FIRE, has been developed. This toolset can assess metrics such as 'clutter level' within the image. A range of validation studies have been undertaken throughout the development of CAMEO-SIM. This paper will give an overview of the current capabilities of CAMEO-SIM and describe planned developments. The validation work will be reviewed, especially the recent work on thermal modelling and analysis using FIRE.
When using synthetic imagery it is essential that it is fit for purpose. Imagery can be rendered at different levels of quality, depending on application. For example, when using a real-time system, rendering speed is a critical parameter but, when assessing the effectiveness of a camouflage system, physical accuracy is likely to be more important. A method to quantify the accuracy of the imagery, for particular applications, is necessary. A range of different metrics based on wavelets, higher order statistics, and a human vision model, has been developed to assess the fidelity of synthetic imagery. These metrics have been used to analyze synthetic imagery rendered at different levels of fidelity and to compare the synthetic imagery with real- world imagery. Some of the metrics can be used to compare two spatially correlated images, whereas others can be used to assess particular characteristics of the image such as clutter level. The metrics, and first order statistics, have been incorporated into a tool box called FIRE (Fidelity Investigations and Reporting Environment). This paper will describe the metrics used and the results of analyses undertaken.
CAMEO-SIM was developed as a laboratory method to assess the effectiveness of aircraft camouflage schemes. It is a physically accurate synthetic image generator, rendering in any waveband between 0.4 and 14 microns. Camouflage schemes are assessed by displaying imagery to observers under controlled laboratory conditions or by analyzing the digital image and calculating the contrast statistics between the target and background. Code verification has taken place during development. However, validation of CAMEO-SIM is essential to ensure that the imagery produced is suitable to be used for camouflage effectiveness assessment. Real world characteristics are inherently variable, so exact pixel to pixel correlation is unnecessary. For camouflage effectiveness assessment it is more important to be confident that the comparative effects of different schemes are correct, but prediction of detection ranges is also desirable. Several different tests have been undertaken to validate CAMEO-SIM for the purpose of assessing camouflage effectiveness. Simple scenes have been modeled and measured. Thermal and visual properties of the synthetic and real scenes have been compared. This paper describes the validation tests and discusses the suitability of CAMEO-SIM for camouflage assessment.
The spatial and spectral characteristics of targets and backgrounds must be known and understood for a wide variety of reasons such as: synthetic scene simulation and validation; target description for modelling; in- service target material characterisation and background variability assessment. Without this information it will be impossible to design effective camouflage systems and to maximise the capabilities of new sensors. Laboratory measurements of background materials are insufficient to provide the data required. A series of trials are being undertaken in the UK to quantify both diurnal and seasonal changes of a terrain background, as well as the statistical variability within a scene. These trials are part of a collaborative effort between the Defence Evaluation and Research Agency (UK), Defence Clothing and Textile Agency (UK) and the T.A.C.O.M. (USA). Data are being gathered at a single site consisting primarily of south facing mixed coniferous and deciduous woodland, but also containing uncultivated grassland and tracks. Ideally each point in the scene needs to be characterized at all relevant wavelengths but his is unrealistic. In addition there are a number of important environmental variables that are required. The goal of the measurement programme is to acquire data across the spectrum from 0.4 - 14 microns. Sensors used to include visible band imaging spectroradiometers, telespectroradiometers (visual, NIR, SWIR and LWIR), calibrate colour cameras, broad band SWIR and LWIR imagers and contact reflectance measurement equipment. Targets consist of painted panels with known material properties and a wheeled vehicle, which is in some cases covered with camouflage netting. Measurements have bene made of the background with and without the man- made objects present. This paper will review the results to date and present an analysis of the spectral characteristics fo different surfaces. In addition some consideration will be given to the implications of the data obtained for camouflage design.
Computer generated imagery is increasingly used for a wide variety of purposes ranging from computer games to flight simulators to camouflage and sensor assessment. The fidelity required for this imagery is dependent on the anticipated use - for example when used for camouflage design it must be physically correct spectrally and spatially. The rendering techniques used will also depend upon the waveband being simulated, spatial resolution of the sensor and the required frame rate. Rendering of natural outdoor scenes is particularly demanding, because of the statistical variation in materials and illumination, atmospheric effects and the complex geometric structures of objects such as trees. The accuracy of the simulated imagery has tended to be assessed subjectively in the past. First and second order statistics do not capture many of the essential characteristics of natural scenes. Direct pixel comparison would impose an unachievable demand on the synthetic imagery. For many applications, such as camouflage design, it is important that nay metrics used will work in both visible and infrared wavebands. We are investigating a variety of different methods of comparing real and synthetic imagery and comparing synthetic imagery rendered to different levels of fidelity. These techniques will include neural networks (ICA), higher order statistics and models of human contrast perception. This paper will present an overview of the analyses we have carried out and some initial results along with some preliminary conclusions regarding the fidelity of synthetic imagery.
Synthetic imagery is now used by a variety of military applications. In our application, we are using synthetic imagery to study the effectiveness of different camouflage techniques. The requirement is to be able to display high fidelity imagery of target vehicles against different background in different wavebands. For a complete assessment of camouflage the system should be able to account for the effect of target motion, interactions between the target and its environment and effects such as hot sources, e.g. engines. CAMEO-SIM has been developed to meet these requirements. It can generate physically accurate radiance images in any EO waveband between 0.4 and 14 microns. Sensor effects are added as post-process. The system is capable of modelling highly cluttered terrain scenes and delivers radiance values at each pixel. Recent extensions to CAMEO-SIM include true-color visible band imagery and simple multispectral image display for simulation of hyperspectral imagery. Visible band images are displayed on a calibrated monitor for assessment experiments using observers. Radiometric data are used by other models. A range of verification tests has shown that the software computes the correct values for analytically tractable scenarios. Validation tests using simple scenes have also been undertaken. More complex validation tests using observer trials are planned. This paper will describe the current version of CAMEO-SIM and how images it produces are used for camouflage assessment. The verification and validation tests undertaken will be discussed. In addition, example images will be used to demonstrate the significance of different effects such as spectral rendering and shadows. Planned developments of CAMEO- SIM will also be outlined.
The signature of any vehicle does not exist as an entity in its own right, but depends on the environment, the interaction between the environment and the vehicle, and the background against which it is detected by a sensor. CAMEO-SIM was initially developed as a broad-band (0.4 - 14 micron) scene generation system for the assessment of air vehicle camouflage effectiveness, but it can be used to simulate any kind of object and its interactions with the environment. The thermal, spectral, spatial and directional effects of sources, surfaces and the atmosphere are modeled in a fully three-dimensional environment. CAMEO-SIM was designed to be a scaleable system that can produce images to different levels of fidelity. Rendering time can be balanced against the fidelity required so that the images produced are 'fit for purpose;' in its lowest fidelity operation it can create real-time in-band imagery but when operated at its highest fidelity the subtle, complex spectral and spatial effects that arise in the real- world are more closely captured. This paper describes the current system, details the verification tests that have been undertaken, and discusses the significance of particular effects such as shadows, and directional reflectance, on the accuracy of the final image.