FIR-estimated filament parameters for single-dust models (COM, CMM, or AMMI) and two models with spatial dust-property variations. In CMM(2), the transition is from normal CMM dust in the outer parts to modified dust with β = 1.5 in the inner part. For COM/AMMI, the transition is from COM dust to AMMI dust. The filament column density is N(H₂) = 3 × 10²² cm⁻², and the filament is illuminated by an isotropic radiation field (frames a–d) or with a 590 L_⊙ point source at Δy = 2.09 pc and 0.93 pc to one side of the filament (frames e–h). The plotted parameters are the estimated optical depth relative to its true value (τ/τ₀), the parameters R and p of the fitted Plummer functions, and the resulting filament FWHM estimate.