Top panel: Angular diameters obtained from the fit of AMBER visibilities with a UD model, separately for each line of a mask. Lines belonging to a given mask are coded in the corresponding color (see Fig. 3). Dashed horizontal lines correspond to the UD diameters obtained from a UD-model fit of all AMBER visibilities contributing to a given mask at once. Shaded areas correspond to errorbars. Middle panel: same as top panel for the best-matching 1D CODEX model (see Sect. 4.2). Bottom panel: same as top panel for the best-matching snapshot from the 3D RHD simulation (see Sect. 4.3).