Evaluation of the Suitability of Polarimetric Scattering and Emissivity Models with Scene Generation Software

Software based polarimetric image generation models and hardware based infrared scene projectors commonly utilize analytical forms of polarized bi-directional reflectance distribution function and emission models. Many of these models are based in first principles physical concepts, but in practice are configured as least error fits to measured signatures. The resulting analytical model may well describe the lab measured data points, but provide erroneous results when integrated into a wide ranging radiometric simulation environment. In this work we present a methodology for characterizing the suitability of incorporating limited range lab measured data, usually through fitting to an analytical model, into a wider range modeling environment. We have found lab measured reflectance data can be fit to analytical models with parameters straying significantly from the first principles physical description of the surface. This effect may be due to over parameterization or an under sampled measurement space, resulting in radiometric anomalies when integrated into a larger scale, multi-surface, multi-material, modeling environment. Our methodology consists of a series of sanity tests that each scattering and emission model configuration must pass before confidence is had in the polarimetric optical property description.