Radial profiles of different quantities for disks with different filling factors (colours). The reference disk model (solid lines) is shown in a comparison with different disk models (dashed lines): a disk with a dust mass M_dust = 10⁻⁵ M_⊙ lower by a factor of 10 (first column), a disk with a dust mass M_dust = 10⁻³ M_⊙ higher by a factor ten (second column), a disk with a maximum grain size s_max = 100 μm smaller by a factor ten (third column), and a disk with a maximum grain size s_max = 10 mm larger by a factor ten (fourth column). Top: degree of polarisation for scattering only, i.e. without the unpolarised direct re-emission. Middle: flux ratio of scattered to direct re-emission. Bottom: net degree of polarisation of the total flux, i.e. scattered and direct radiation, including vertical error bars.