(a) Two diffracted propagation paths. On the left building, the path is diffracted around the entire building with an accumulated diffraction angle φ _A  > π. The right building shows a diffracted path with φ _A > 2π. Depending on the angular threshold value, these paths are dismissed. (b) Wedge with aligned faces F ₁ and F ₂. Propagation paths to edges that are completely located in the illuminated region of both aligned faces (red area) are diffracted neither from the shadow region of F ₂ nor from the shadow region of F ₂.