Same as Fig. 1 but colour coded with the median of the stellar metallicity [M/H] in each pixel. In the Galactic plane, the higher metallicity values of the thin disc are visible. In the central Galactic regions, a more metal-poor mix of bulge and thick disc populations is present. Far from the disc plane, high-metallicity thin disc stars at low distances from the Sun and more distant metal-poor halo stars are present.