Change Detection of Landslide Terrains Using Ground-based Lidar Data

The topographic change has been estimated on basis of 3D laser data and aerial photogrammetric survey. The newly-developed, time-saving approach is by using airborne and ground-based lidar. A points-cloud of high precision and density distribution can be obtained in a few minutes for the sensitive latent landslide area. With a limited control survey of precise targets using GPS and total stations, multiple scans of ground-based laser scans can be registered together to form one cohesive 3D model. And, thus, overlaid the different period topographic data for estimating the changes of the target areas. Two cases are practiced in this study. For the first case, a river-bank landslide in Hsin-chu Hsien was scanned with 6 stations. Subsequently, they were registered and joined and re-sampled to a 2m grid for a comparison with information obtained by digitization of a 1/5000 topographic map. The second case is conducted to observe the deformation of a large-scaled dip-slope landslide of Jiu-fen-er mountain, which was triggered by the big shock of the Chi-Chi earthquake at Nantou County of central Taiwan on 1999/09/21. Control points are systematically distributed on the 1000m by 2000m landslide surface. Surveys are made by transits of total stations, GPS, and airborne lidar as well as ground-based lidar data. The terrain changes on ground surface have been detected in thus a scheme. It is found the largest change of height between the earthquake event is about 60m. The effectiveness of applying 3D laser scan is proved in this study.