| Laser range finders and total stations have been used, although rarely, for 3D digital mapping and analysis of geological outcrops. High speed Terrestrial Laser Scanners (TLS), also known as ground LiDAR, are used in a variety of methods for analyzing geological outcrops and terrain features. Most of these applications use point clouds (colored or uncolored) of the scanned surface as the analytical database. By converting the point cloud into a photorealistic 3D surface model, the visual fidelity of the model is significantly improved, greatly enhancing the analytical potential of the model. This work describes the extension of both the laser range finder/total station method and the TLS method into a widely used GIS (Geographic Information System) software platform, ESRI ArcGIS. The ArcGIS platform provides an effective user interface and the ability to link the analytical results saved in attribute tables to geometric features that are placed into the 3D model. The techniques that have been developed can convert 3D models that are saved in either the Wavefront OBJ format or the Virtual Reality Modeling Language (VRML) into the ESRI 3D multipatch format. Point cloud representations of the model can also be loaded into the ArcGIS software. Orientation and visualization tools for strike-dip, trend-plunge, fault and fold surfaces, down-plunge cross-section and distance measurement tools have been implemented in the 3D ArcScene and the 2D ArcMap extensions of ArcGIS. The results from capturing outcrop data using laser rangefinders and total stations were demonstrated in support of a geology field methods class on outcrops in the Permian age rocks of the Slick Hills area, Oklahoma. In conjunction with staff from the University of Calgary models of sandstone outcrops along the Milk River at Writing on Stone Provincial Park, Alberta, Canada were constructed to demonstrate the use of TLS to enhance the characterization of petroleum reservoir models. 3D models of Cambrian limestone/dolomite and Ordovician limestone in the Arbuckle Anticline region along Interstate 35 in southern Oklahoma were made to demonstrate the analysis tools for orientation, faulted and folded surfaces, and as a test bed for the development of educational applications of the tools. |
