TERRESTRIAL LASER SCANNING FOR LANDSLIDE MOVEMENTS DETECTION

The development of Terrestrial Laser Scanning (TLS) method for the generation of DTMs has made great progresses in objects measuring, reaching high resolutions and completeness in models reconstruction. Nowadays it is an essential tool that can be used to detect, better classify and monitoring landslides, although it's not always clear the internal precision that characterise the DTMs generated. Moreover there are some open problems concerning data processing and procedures used to generate DTM from Digital Surface Models (DSMs), extracting artificial objects and vegetation. Remarkable is the option, available in specialized software, of co-registration of DTMs realized in different periods, even in absence of classical ground control points. This option is developed to reduce to a unique reference system the acquired clouds of points. Nevertheless, when feasible, it is advisable to use the standard and more accurate geo-referencing methods based on a 3D similarity transformation applied on sets of common unchanged points. The paper refers to DTMs derived from TLS surveys for a landslide located near Bologna (Italy), and particularly shows the comparison between DTMs obtained from TSL and digital aerial photogrammetry. Selected aspects of data processing and representation are reported, in order to evaluate the accuracy and the reliability in restitution of the terrain shape