GHASP (panel (a)) and simulated Hα surface brightness (panels (b) and (c)) of NGC 4330, with scales identical to those used in Fig. 2 (d), i.e. with a threshold limit Σ(Hα) ≃ 10⁻¹⁷ erg s⁻¹ cm⁻² arcsec⁻². The low level cuts used to display the simulated Hα images have been chosen to show the low column density ionised gas reached by the simulations (panel (b)) and at higher surface brightness levels (Σ(Hα) ≃ 2×10⁻¹⁷ erg s⁻¹ cm⁻² arcsec⁻²; panel (c)), matching the typical surface brightness limit of VESTIGE and FP observations, respectively.