Fig. 4

Horizontal cross-section of the 3D checkerboard test with dimensions of approximately 9 km \(\times\) 9 km \(\times\)1.5 km in width, height and depth, respectively. The synthetic maps at different depths are shown in panels (A), (C), (E), (G) and (I). The corresponding recovered Qc-1 maps at different depths are shown in panels (B), (D), (F), (H) and (J), respectively. The digital elevation model was sourced from GRAFCAN’s repository (www.grafcan.es), and the figure was generated using the Matplotlib Python package57.