Best-fit value of OE parameters (HWHM and ζ) with respect to the wavelength for six ROIs. Each plot presents two ROIs that are grouped based on the different geomorphological classes, smooth regions (ROIs 1 and 3), talus regions (ROIs 2 and 6), and consolidated regions (ROIs 4 and 5). The dashed lines represent the weighted linear fit. Different symbols are used for different ROIs. Left column: wavelength dependence of ζ. Right column: wavelength dependence of the HWHM.