Three dimensional surface movement detection using terrestrial laser scanning method

For the past years, numerous conventional and modern surveying methods have been used in landslide studies. Since landslide evolves continuously as a result of natural processes, better and faster tools related to generating more realistic three dimensional (3D) Digital Terrain Model (DTM) representation of the landslide sites are desired. Recently, Terrestrial Laser Scanning (TLS) has been recognized as the most promising remote sensing techniques for geohazard studies. It offers very high resolution of spatial sampling in 3D measurement in a short time and also without contact with the hazardous area. The aim of this study is to evaluate the capability of TLS technology in landslide investigation. Leica ScanStation2 scanner was utilized to obtain 3D cloud points of landslide area at Institut Tanah Ukur Negara (INSTUN), Ulu Behrang, Perak, Malaysia. Several ground control points (GCP) were established for georeferencing purpose using Trimble R8 receiver whereby the local coordinates of the GCP were derived from Malaysian Real Time Kinematik network (MyRTKnet). The commercial software Cyclone 6.0 was used to process the target-based registration and produce DTM. The processing result has shown that the use of three tie-points is very sufficient for registration and georeferencing process which gave the maximum constraint value within 24mm, and about 16mm for Root Mean Square (RMS). The accuracy assessment of DTM comparison gave the standard normal distribution of errors after re-registration process using surface matching method. The landslide investigation was conducted and the displacement detected with range from -0.538m to 0.678m. The overall result of this study shows that TLS is an effective tool in detecting the surface movement of the landslide prone area