## 3 Results
along an artificial trench (Monte Ercta) carved into Mesozoic limestone in the 1950s. The survey of the mesostructure, carried out using traditional techniques (scanlines and Clarr compass), terrestrial photogrammetry [53], and laser scanning, revealed the same oriented structure characterized by four main families of discontinuities. Two families (set 2 and set 4) have a \"direction\" sub-parallel to the wall, while the other two (set 1 and set 3) have a direction almost orthogonal to the trench. The surveys were conducted using the RIEGL LMS-Z210 laser scanner, featuring a scanning field of 80\({}^{\circ}\)\(\times\) 360\({}^{\circ}\). It is capable of measuring up to a distance of 486 m with a precision of 14 mm, using programmed angular steps. The acquisition speed can reach up to 9387 points/s, and the wavelength of the emitted beam is 1\(\upmu\)m. The laser scanner was positioned at a minimum distance of about 10m, and the scan was executed with a resolution of 0.018\({}^{\circ}\). For reflectivity evaluations, a section of the wall was chosen where discontinuities coexist, exceeding 1m\({}^{2}\) in extent, with different types and degrees of alteration. On the discontinuities characterized by smooth surfaces in the upper portion (Figure 2a), which exhibit a corroded and vacuolar appearance near the roadbed, the measured values of reflectivity (\(I\)) range from 35% to 55%. The lower values (I = 35% \(\div\) 45%) are associated with fractured rock, resulting in the wall having pronounced small-scale roughness. Similar values were measured at the altered discontinuities with surfaces rendered rough due to the presence of pores and vacuoles. In the presence of altered but smooth surfaces with a uniform texture (Figure 2b), the measured values of \(I_{m}\) averaged approximately 47%. Intact and slightly altered rock (Figure 2c) provided an average \(I_{m}\) value of 52.5%. These measurements were compared with rebound values (\(r\)) obtained using the Schmidt hammer. In the zone dominated by fractured rock and an altered discontinuities with a corroded and vacuolar surface, the average rebound value (\(r_{m}\)) range is 31%. On altered discontinuities with a uniform surface, the average rebound value (\(r_{m}\)) is 42%. On slightly altered surfaces or massive rock, average rebound values (\(r_{m}\)) are 52%. In the first zone (fractured rock), it is highly likely that the results are influenced by the extremely variable volume of rock fragments on which the measurements were taken. As the value of I increases, there is also an observed increase in the rebound value (\(r\)). Survey 2. The second site chosen for a laser scanner survey is one of the abandoned quarries of dolomitic limestone located on Monte Catalfano near Bagheria (Palermo) (Figure 3). The quarry face, measuring 10,000m\({}^{2}\), has a height of 120m. Considering the technical specifications of the laser scanner, the morphology of the object to be scanned, and the features to be captured (meso-structural arrangement and roughness characteristics of the discontinuities), the scan points were planned to ensure a minimum overlap percentage of 30% between individual scans. The FARO FOCUS 3D laser scanner, with a scanning range of 305\({}^{\circ}\)\(\times\) 360\({}^{\circ}\) and the ability to measure up to a distance of 120 m with programmed step angles, was positioned approximately 15m away from the wall. The acquisition speed can reach up to 976,000 points/s. The emitted laser beam has a wavelength of 0.90 microns. For the necessary three-dimensional rendering of the surveys and subsequent roto-translation operations, it was planned that at least eight points on the wall would be recognizable in each capture. Figure 2: Monte Pellegrino: portions of the wall characterized by different degrees of alteration. Schmidt hammer estimations (\(r_{m}\)) and reflectivity measured by the laser scanner (\(I_{m}\)): (**a**) smooth surfaces (**b**) altered but smooth surfaces with a uniform texture (**c**) intact and slightly altered rock.