Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

Parameter-based imaging from passive multispectral polarimetric measurements

“…However, if the illumination polarization is known, the extension of the analysis to this case is relatively straightforward. We note that the fourth Stokes component, corresponding to the circular polarization state, is not measured by the Ground-MSPI due to its insignificant contribution in most natural scenes [1][2]4,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

“…In this section, we summarize the modified polarimetric bidirectional reflectance distribution function (pBRDF) model and the parameter estimation approach used for this work [14]. Figure 1 defines the scattering geometry for the pBRDF and the measurements.…”

“…For this work we separate scattering phenomena into two general categories: surface and diffuse [9][10][11][12][13][14]. Surface scattering occurs at the interface between air and the target surface.…”

“…We assume the diffuse scattering is completely unpolarized and Lambertian where the light encounters enough multiple scattering events within the bulk of the material that the scattering directions and polarization state are uniformly random. In general, the diffuse scattering may exhibit some polarization and directional preference due to the re-emergence processes [23], but the assumptions of unpolarized and Lambertian scattering are reasonable especially for remote sensing scenarios where the target's surface roughness is typically large compared to the incident wavelength [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In contrast, the surface scattering that develops based on a microfacet model, can produce a directional lobe and polarization preference.…”

“…In recent studies [13][14], we describe two independent approaches for estimating the refractive index, roughness and diffuse scattering coefficient of a surface from measurements of the degree of polarization (DOP) and the Stokes parameters, respectively. Theoretical developments were presented that incorporate a diffuse scattering component in the description of the observed DOP and Stokes signals.…”