Three-dimensional structure of the LHB in the western Galactic hemisphere assuming a constant density of 4 × 10⁻³ cm⁻³. The inner (opaque, coloured) and the outer (grey, translucent) surfaces show the ±1 σ uncertainty bounds of the distance under the constant n_e assumption. We note that the two surfaces only reflect the uncertainty in the spectral fitting but not in n_e. We note that kT_LHB is also colour-coded on the inner surface. A sphere of 100 pc radius is shown around the Sun (yellow) as a ruler. An interactive version of this figure, including the comparison with dust maps (not shown) can be accessed from online or the accompanying website (Sect. 5).