VLTI/MATISSE squared visibility data, denoted V², in logarithmic scale (top plot) and closure phase data, denoted CP, (bottom plot) of 3 Puppis in the L- (blue), M- (green), and N- (red) bands, plotted as a function of spatial frequency B/λ. The vertical dashed lines indicate the approximate positions of the first visibility nulls in the three bands with the same colour code. The horizontal dashed line marks the visibility plateau at long baselines in the L-band, which reflects the relative flux contribution from the unresolved central source.