A Phenomenological Polarized Spectral Bidirectional Reflectance Distribution Function Based on Spectral and Spatial Dependence

The polarized bidirectional reflectance distribution function (pBRDF) model not only quantifies radiation intensity, but also effectively describes the polarization characteristics of the scattered light on the target surface. In this paper, the spectral and spatial dependence of specular and diffuse reflection of four coating fabric samples are analyzed, which are defined as the dependence on wavelength and observation positions. The analysis shows that the specular reflection has no spectral and a strong spatial dependence; the diffuse reflection has a strong spectral and weak spatial dependence. Based on the analysis, a phenomenological polarized spectral bidirectional reflectance distribution function (pSBRDF) is proposed, which further divides the diffuse reflection into directional diffuse reflection with both weak spectral and spatial dependence, and ideal diffuse reflection with a strong spectral and no spatial dependence. Then, the degree of linear polarization (DoLP) model is derived, when the incident light is natural light. The comparison of measured and modeled results shows that the model can accurately describe the spectral and spatial dependence of reflection and polarization of four samples, which provides theoretical support for analyzing the polarized spectral characteristics of targets.