Face-on view on the Milky Way disc with Gaia DR2: spatial and guiding coordinate space. Panel a: two-dimensional map in the Galactic plane of the number of Gaia DR2 stars with radial velocities, colour-coded by number of stars. The grey oval represents the orientation of the Milky Way bar (Wegg et al. 2015), and the solar position is shown by a yellow star. The stellar density distribution is shaped by the Gaia footprint and is heavily influenced by the fading of stars at greater distances and by the high interstellar extinction in the Galactic plane. Panels b and c: two-dimensional map in guiding coordinate space of the mean number of stars over 100 random samples drawn from the homogenized spatial density map ρ(X_g, Y_g). Panels d and e: unsharp masking map (see Eq. (2)) of the guiding space showing six newly discovered overdensities prominent in a wide area of the Milky Way disc, each containing between 2000 and 6000 stars, about 5–12% of the respective background. This estimate is a lower limit for the amplitude of the overdensities because of the dust extinction in the disc plane blurring their visible structure. These features are indicated in panels c and e, and are interpreted below as the imprint of the Galactic bar (corotation and outer Lindblad resonances) and the four-armed spiral structure in the Milky Way. The irregular vertical features near X ≈ 0 line are artefacts of the Gaia DR2 footprint in this area.