An objective method for the assessment of levelness of dyed materials has been established. The relative unlevelness index developed takes account of the coefficients of variation of reflectance measured over the visible spectrum, with appropriate consideration of human vision sensitivity. It was found that the index demonstrated good correlation with the visual levelness assessment.

Owing to limited land resources and unique ecosystems, islands face more serious ecological risks under the interference of climate change and human activities. In this study, selecting Zhoushan Island as the study area, a landscape ecological risk index model was constructed based on LULC (land use/land cover) data and the landscape ecological risks for Zhoushan Island from 2000 to 2020 were analyzed. The results showed that: (1) From 2000 to 2020, the proportion of forest land and grassland remained above 70%, built-up land expanded from 52.67 km2 to 123.52 km2, and the beach area and ocean on the north side of the island decreased by 23.24 km2 and 24.87 km2, respectively; this was mainly converted into built-up land. (2) The number of landscape patches in Zhoushan Island decreased as the landscape ecological risk index decreased. The landscape ecological risk showed distinct spatial autocorrelation, with lowest-risk and medium-risk areas collectively accounting for 80% and higher-risk and highest-risk areas showing a decline. (3) The landscape ecological risks exhibited distinct spatiotemporal differences. Before 2010, the higher-risk and highest-risk areas were mainly distributed in the mudflat and ocean areas on the northern coast. After 2010, the higher-risk and highest-risk areas are mainly distributed in the central region, which comprises woodland, grassland, and built-up land.