Tracing structure along sightlines. Left panel: a (205, 0.2, 0.2) h⁻¹ cMpc line of sight segment traversing a TNG snapshot at z = 0. The grey line indicates the sightline through the segment. Blue squares projected onto the (xy, yz, xz) planes represent the number density of all cells within the segment in the (x, y, z) directions. Dots coloured according to their LSS type represent the central locations of all cells identified as closest to one of the 10 000 bins along the sightline. The sightline is approximated to traverse these cells due to the Voronoi tessellation of the simulation. Right panel: a second sightline complete with the subhalo it traverses and the impact parameter measured between the sightline and subhalo.