Comparison of Lambertian and real energetic sound scattering pattern. A plane wave with incidence in (green) hits a rough periodic surface (black). The reflection pattern of a sinusoidal surface (red) at Λ/λ=2 is determined after Embrechts analytical solution [7] including its direction and energy. The Lambertian model (blue) is discretized in equal angular steps of 15°. The length of the arrows represent their energies. Both reflection patterns result in a random-incident scattering coefficient of 1 as they are normalized in energy.