Ideal and perturbed J-PAS galaxy mock samples (top panels) and void distributions (bottom panels) in X − Y and X − Z projections. We show a 10 Mpc-thick slice for each projection. The effect of redshift errors on the galaxy distribution is evident in the X − Z projection of the perturbed sample (fourth column, top panel). Cross-sections of voids are shown in greyscale, while colours highlight voids that have more than 50% volume overlap between the ideal and perturbed samples (see Sect. 3.2.1 for further discussion). A visual comparison reveals that voids detected in the ideal sample tend to fragment into various-sized voids in the perturbed sample.