Where ( \alpha = \textRoughness^2 ) (in V-Ray’s remapping). This distribution has a higher kurtosis than Beckmann, producing brighter specular cores and more pronounced falloff—critical for anistropic metals.
For conductors (metals), V-Ray uses the ( \tilden = n + ik ), where ( k ) is the extinction coefficient: vray materials
[ f_r = f_diffuse + f_specular ] For perfectly rough surfaces, V-Ray defaults to the Lambertian model (constant albedo). However, for rough, clay-like materials, V-Ray implements the Oren-Nayar model, which accounts for retro-reflection: Where ( \alpha = \textRoughness^2 ) (in V-Ray’s remapping)
Where ( \alpha = \max(\theta_i, \theta_o) ), ( \beta = \min(\theta_i, \theta_o) ). This prevents the unnatural darkening seen in pure Lambertian materials at grazing angles. V-Ray abandoned the Blinn-Phong and Ward models in favor of GGX (Trowbridge-Reitz) for its ability to produce realistic long-tailed highlights (i.e., the "glint" of metallic paint). The distribution function ( D(m) ) for microsurface normals is: The distribution function ( D(m) ) for microsurface