Comparison between the maps of median Z-coordinate from observations, best-fit model and residuals. Top-left: median Z-coordinate of the young giant sample. The position of the Sun is shown by the black cross at (X,Y)=(0 kpc, 0 kpc). Middle: prediction from the m=1 tilted rings model (left), straight line-of-nodes parametric model (centre) and twisted line-of-nodes parametric model (right). Bottom: corresponding vertical residuals for the m=1 tilted rings model (left), straight line-of-nodes parametric model (centre), and twisted line-of-nodes parametric model (right). Dotted lines in the three lower panels show rings at constant radii of R=10, 12, and 14 kpc from the GC. An interactive 3D view of this figure is available online.