Comparison of the 3D-ring model with the flat disk model. Left: I, Q_d, U_d and Q_ϕ for a 3D disk ring with a full width at half maximum density distribution of Δ_FWHM∕r_ring = 0.2. Scattering parameters are g = 0.6 and p_max = 1 for inclinations i = 0°, 45°, 75° and 90°. The same gray scale from + a (white) to −a (black) is used for all panels. The black lines in the Q_d and U_d panels indicate the polarization quadrants. Right: same but for the flat disk model.