Model image of G033.3891 of the 2.2 µm continuum emission (thick ring) combined with the Brγ (compact Gaussian) and CO bandhead molecular emission (thin bright ring). The modelled image of the CO emission is the average of the individual images of the CO bandheads extracted at their central wavelengths (2.29, 2.32, 2.35, and 2.38 µm). The total geometric model (red line) fits well all interferometric observables (closure phases, T3PHI; differential phases, DPHI; visibilities, V; normalised flux, NFLUX) of the continuum, Brγ, and CO bandheads. PMOIRED normalises the flux from both the data and the model using the same algorithm. The grey shades represent the systematic errors of the interferometric observables, taking into account the calibration and transfer function uncertainties. The colour scheme of the different baselines follows Figure 1.