Millimeter fluxes F_mn, as a function of the size of the photoevaporative cavity for the smooth (dotted) and structured (solid) disk models. The solid and dotted lines represent flux from the optically thin approximation (Eq. (15)). The markers are the fluxes obtained with RADMC-3D (“+” for the smooth disk, “x” for the structured disk). The disks are assumed to be at 140 pc, and no inclination. The cavity size measurement is based on the dust distribution of millimeter sized grains.