The Joint Synthetic Battlespace for the Air Force (JSB-AF) is being developed to provide realistic representations of friendly and threat capabilities and the natural environmental conditions to support a variety of Department of Defense missions including training, mission rehearsal, decision support, acquisition, deployment, employment, operations, and the development of Courses of Action. This paper addresses three critical JSB issues associated with providing environ-mental representations to Modeling and Simulation (M&S) applications. First, how should the requirements for envi-ronmental functionality in a JSB-AF application be collected, analyzed, and used to define an Authoritative Environ-mental Representation (AER)? Second, how can JSB-AF AERs be generated? Third, once an AER has been generated, how should it be “served up” to the JSB-AF components? Our analyses of these issues will be presented from a general M&S perspective, with examples given from a JSB-AF centered view. In the context of this effort, the term “representa-tions” is meant to incorporate both basic environmental “data” (e.g., temperature, pressure, slope, elevation, etc.) and “effects”, properties that can be derived from these data using physics-based models or empirical relationship from the fundamental data (e.g., extinction coefficients, radiance, soil moisture strength, etc.) We present a state-of-the-art review of the existing processes and technologies that address these questions.
Proc. SPIE. 5431, Targets and Backgrounds X: Characterization and Representation
KEYWORDS: Reflection, Databases, Computer programming, 3D modeling, Geographic information systems, Bidirectional reflectance transmission function, Solids, Chemical elements, Atmospheric modeling, RGB color model
Vehicles concealed in highly cluttered, vegetated scene environments pose significant challenges for passive sensor systems and algorithms. System analysts working hyperspectral exploitation research require an at-aperture simulation capability that allows them to reliably investigate beyond the highly-limited scenarios that expensive field data sets afford.
To be useful to the analyst, such a simulation should address the following requirements: (1) the ability to easily generate scene representations for arbitrary Earth regions of tactical interest; (2) the ability to represent scene components, like terrain, trees and bushes, to an extremely high spatial resolution for calculation of accurate multiple spectral reflections, occlusions and shadowing; (3) the ability to stimulate the 3D scene with realistic natural spectral irradiances for arbitrary 3D model atmospheres; (4) the ability to appropriately integrate constantly improving, rigorous thermal, spectral signature and atmospheric propagation models; (5) the ability to efficiently render at-aperture hyperspectral data sets in a reasonable run-time.
Herein the authors describe their work toward a comprehensive ray-tracer-based simulation architecture and prototype capability that addresses these requirements. They describe their development of a GIS-based toolset for database generation, tools for 3D vegetated terrain-model development, and a prototype raytracer-based spectral scene generator.
UV-VIS-NIR ratiometric reflectance data was obtained for several commonly utilized remote sensing calibration standards used in Fourier Transform Hyperspectral Imaging. We found that single layer reflectance depends on the degree of translucency and hence on the particular choice of background material, from which multiple layer reflectance and extracted absorption and scattering curves logically follow. These data are given as a function of incident wavelength for each calibration standard. Because optical properties are determined by the combination of scattering and absorption, we deconvolved their effects on each material's spectrum.