Comparison between the orbital images and the simulated illumination results over the study area. Panels (a) and (b) show the orbital NAC images from the LROC products M1415076933RE/LE and M1443223691RE/LE, respectively. Panels (c) and (d) present the DEM-based simulated illumination maps without smoothing, whereas panels (e) and (f) show the corresponding Gaussian-smoothed results. For ease of comparison among panels, the simulated illumination intensity is normalized to the range 0–1, and the color scale indicates the normalized illumination.