KiDS-DR3 footprint binary mask (Hildebrandt et al. 2017), pixelated with HEALPIX (Górski et al. 2005), with a resolution given by N_side = 512. The top and the middle panels cover the extension of KiDS-N, while the bottom panel refers to KiDS-S. Clusters are distributed within the unmasked area (yellow). Small holes and irregularities reflect the presence of severe incompleteness and substantial photometric degradation, due to satellite tracks, stars etc.