ρ Ophiuchi cloud model. The plots show the mean values of the effective total column density PDFs, , as a function of the inclination, θ, and position angle, ϕ. The error bars illustrate 1σ errors. Note that we only show the values for inclinations θ ≤ 180° because the values for θ and θ+180° are identical. We see that the mean dust column density strongly depends on the viewing angle. The maximal difference compared to (θ, ϕ) = (0°, 0°) is on the order of 1.7 dex.