Variations of the averaged weighted emission intensity (Ī) (top left), (bottom left) and r^TE (bottom right) as a function of the azimuthal position of the observer (ϕ_⊙ [°]) for the different galaxies (indicated in the captions) and for different values of sky fraction (f_sky, indicated by the colors in the legend). Top right: evolution of the averaged dust density (normalized to the sample median) in spheres of radii (100 pc, 200 pc and 500 pc) around an observer as a function its azimuthal coordinate (ϕ_⊙). The colors represent different values of the radius of the sphere surrounding the observer as informed by the legend. Spheres are independent if their ϕ_⊙ differ by at least 1.43°, 2.86° and 7.16° for radius R_sph of 100 pc, 200 pc, and 500 pc, respectively. The vertical gray bands indicate the range of ϕ_⊙ values in which we consider the observer to be located in the arms (see Sect. 4.4.1).