Geomorphological and speleogenetical observations using terrestrial laser scanning and 3D photogrammetry in a gypsum cave (Emilia Romagna, N. Italy)

Terrestrial Laser Scanning (TLS) and 3D photogrammetry techniques were used in a relatively small (100-m-long) cave developed in Messinian gypsum in Emilia-Romagna (N. Italy). The surveys were carried out to compare the results obtained by both methods in mapping small-to medium-sized morphologies. These measurements allowed reconstructing the evolution stages of the paragenetic (anti-gravitative) morphologies (ceiling channels and pendants) that carved the roof of the cave, and their relationship with local geomorphology, infilling sediments, speleothems, and structural elements. Field measurements were integrated with morphometrical analyses of the digital models that then allowed a much greater number of observations to be made. The results are a clear example of how the combination of TLS and 3D-photogrammetric data can be used to study and measure mm- to dm-scale morphologies in geomorphological studies, including caves, helping to unravel the speleogenetic and, consequently, the hydrological evolution of these environments