Optimization of LiDAR scanning and processing for automated structural evaluation of discontinuities in rockmasses

Terrestrial light detection and ranging (LiDAR) can be used for the delineation and evaluation of geomechanically controlled hazards. The United States Geological Survey [1] has adopted the use of LiDAR through numerous projects, as discussed in [2]. Other examples of the use of LiDAR surveys for geological data collection include discussion of the process of acquiring digital outcrop models for stratigraphic modelling [3], mapping basalt flow units [4], structural mapping of a large landslide [5], and evaluation of rockfall source and accumulation zones [6,7]. In non-geologicalbased applications, LiDAR has been used for projects ranging from volumetric analysis in open pit mines [8], to recording and cataloguing archaeological digs in ancient ruins [9]. The equipment mobility, accuracy, and rate of data collection, in comparison to conventional surveying and stereophotogrammetric methods, have allowed existing surface analysis projects to proceed at unprecedented levels of detail and have promoted new applications. The use of terrestrial (ground based) LiDAR as a structural analysis and measurement tool has been investigated in detail by Kemeny and Post [10], Feng and Roshoff [11], Pringle et al. [12], Slob et al. [13] and others. Once the data is acquired and the primary 3D model is generated (as x, y, z data points with intensity scalars or mapped colourization via photo coupling), the analytical process can proceed in a similar fashion to modern photogrammetric techniques such as those applied by Haneberg et al. [14]. Both applications can replace traditional field mapping processes including the use of a compass or inclinometer to measure orientation, photos and notebooks to keep records, and manual data entry. Further, the conventional measurement of