Light scattering by closely packed particulate media

We have calculated the scattering of light by media consisting of densely packed spherical particles by applying geometric optics and Monte Carlo simulation. We found that when the packing density is increased, dark surfaces are clearly brightened, especially near grazing emergence and incidence. Also, the transmission through a finite layer is reduced with opaque particles but not with transparent ones. The results indicate that previous models that use low-density approximations (Lommel–Seeliger, Hapke, Lumme–Bowell, etc.) are not accurate for typical regoliths.