Different views of the NFFF extrapolation. Panel (a): side view. Panel (b): top view. Panel (c): zoomed-in FOV of the top view. The three negative polarities N1, N2, and N3 are connected to the positive polarities P1, P2, and P3 nearby with small inner spines, and globally to the plage region (large negative polarity region to the east). The squashing factor Q is plotted at the photospheric level in panels (b) and (c) (colored contours) to show the separatrix at the periphery of the fan surface around N1, N2, and N3.