Comparison of remote sensing techniques for geostructural analysis and cliff monitoring in coastal areas of high tourist attraction: the case study of Polignano a Mare (Southern Italy)
Rock slope failures in urban areas may represent a serious hazard for human life, as well as
private and public property, even on the occasion of sporadic episodes. Prevention and mitigation
measures indispensably require a proper rock mass characterization, which is often achieved by
means of time-consuming, costly and dangerous field surveys. In the last decades, remote sensing
devices such as high-resolution digital cameras, laser scanners and drones have been widely used as
supplementary techniques for rock slope analysis and monitoring, especially in poorly accessible
areas, or in sites of large extension. Although several methods for rock mass characterization by
means of remote sensing techniques have been reported in specific studies, there are very few
contributions that focused on comparing the different methods in an attempt to establish their
advantages and limitations. With this study, we performed digital photogrammetry, Terrestrial Laser
Scanning and Unmanned Aerial Vehicle surveys on a cliff located in a popular tourist attraction
site, characterized by complex geological and geomorphological settings, as well as by disturbance
elements such as vegetation and human activities. For each point cloud, we applied geostructural
analysis by means of semi-automatic methods, and then compared multi-temporal acquisitions for
cliff monitoring. By quantitative comparison of the results and validation by means of conventional
geostructural field surveys, the pros and cons of each method were outlined in attempt to depict the
conditions and goals the different techniques seem to be more suitable fo
