2D slices of z_reion fields extracted from a 21cmFAST simulation. The reionisation redshifts are superimposed on the contours (in black) of the patches from the segmentation obtained with DisPerSE (with a persistence level of 0.5-σ). The three panels represent three models (of the DRH simulations set) with different ζ values: models 3 (ζ = 30), 3−2 (ζ = 55), and 3−4 (ζ = 300), from left to right.