Luminosity density fields in 400 × 400 × 1 h⁻¹ Mpc slices at identical z−coordinates of the central region of the SDSS sample, smoothed with kernels of radii 1, 2, and 8 h⁻¹ Mpc (left, middle, and right panels). This figure illustrates the effect of the smoothing length to geometrical properties of clusters and voids. Densities are expressed in logarithmic scale in interval 0.005–15 in mean density units. The colour code is identical in all panels.