Comparison between the observed dependence of FWHM_obs on the distance (gray data points, symbols as in Fig. 1) and that of a radial profile of a filament in Taurus, after reducing the angular resolution of the Herschel map to correspond to the physical resolution of a 18.2″ beam at the observed cloud distances (red diamonds). Dotted lines mark 1, 2, 4, and 5 times the beam size.