TLS Based Determination of the Orientation of Discontinuities in Karstic Rock Masses

One of the major tasks in quantitative description of discontinuities in rock masses is the determination of their spatial orientation. In recent years, Terrestrial Laser Scanning (TLS) allows a three-dimensional point mapping of surface points with high accuracy. By thinning and meshing the mapped points with a specific software tool, the natural surface can be modeled by planar elements and analyzed in standard CAD software. If the surface represents discontinuity planes and if it is not heavily distorted by natural processes such as erosion, a simple algorithm can be used that allows to identify discontinuities and to determine their spatial orientation. The paper describes the application of this method in a karst cave. TLS measurements were carried out under very harsh conditions. The results of the procedure are presented and their validity is proven on a chosen surface area by comparing the results to in-situ measurements with a stratum compass.