Geological planes such as joints, faults or foliation are key features to unravel the mechanical properties and predict its behaviour in certain stress states. Measuring their spatial attitude (dip and dip direction) is generally performed by hand with a geological compass, which is time consuming and contributes some degree of bias (i.e. features that are rendered irrelevant at the time or in a hazardous location). To extract rock discontinuities and their orientation in sub surface applications using high density 3D point clouds is the aim of this thesis. In the first part a parameter study is conducted to find the right set of parameters for the freeware Discontinuity Set Extractor, published by (Riquelme et al. 2014), for the given geology at Kitzsteinhorn in the Hannastollen; it is made up from rocks of the Bündnerschiefergruppe, its main components are lime mica schist, prasinite, amphibolite, phyllite and serpentinite. The study shows clear tendencies how to create a solid output. The higher the number of nearest neighbour is the more precise the result will be, with the disadvantage that the computing effort increases far above average. The tolerance setting was found, when set to a low threshold to produce, more different sets of discontinuities. During the case study the results from the freeware Discontinuity Set Extractor where compared to a geotechnical report. Large connected structures such as slickensides are stably detected, as well as, the foliation. The accuracy lies in a range of 10° both in dip and dip direction. Small structures, which are not sufficiently represented in the point cloud, are not detectable. In general the method should not be seen as a substitute for geotechnical fieldwork, but more as a complimentary and powerful method adding quantitative data to the traditional surveying method.