Different representations of the volume densities reconstructed for the simple example illustrated in Fig. 1. Top: density profile along lines of sight corresponding to the different environments in the map (diffuse background, intermediate density envelope, dense core, small isolated clump). The nested dense structures are represented in the mid-plane along the line of sight only by convention. Bottom: PDFs of volume densities along the line of sight corresponding to the above lines of sight. The densities are expressed in the same arbitrary units as in Fig. 1. The statistical weights are equivalent to depths along the line of sight, as represented in the top panel.