Stellar density maps of a galaxy and companion satellite at z = 0.4 as obtained by HOP (top left panel) and AdaptaHOP (top right panel). Stellar mass and effective radius are M_s = 2.14 × 10¹¹ M_⊙ and R_eff = 39 kpc, and M_s = 1.25 × 10¹¹ M_⊙ and R_eff = 3.3 kpc for HOP and AdaptaHOP respectively. The resulting size-mass relations (plotted as in Fig. 12) are affected by the galaxy finder as shown in the two bottom panels (left: HOP; right: AdaptaHOP).