Laser rangefinders and ArcGIS combined with three-dimensional photorealistic modeling for mapping outcrops in the Slick Hills, Oklahoma

Abstract

The mapping of geology is conventionally done visually in a hands-on fashion, and the data are recorded in a field book or with photography. An alternative technique that combines reffectorless laser rangefinders or high-speed terrestrial laser scanners, global positioning system, and the Environmental Systems Research Institute (ESRI) ArcGIS software platform has been developed that is effective for mapping geology at a distance and in three dimensions. Portable handbheld reflectorless lasers are used to capture geologic features such as contacts and terrain and can be combined with digital elevation models in ArcGIS software. Fast terrestrial laser scanners capture an entire exposure at the detail and accuracy of (3D) photorealistic (virtual) models with the additional color information from image pixels. This latter method is expensive and complicated and requires significant amounts of field and processing effort. The laser gun approach is simple, portable, and cost effective. When integrated with ESRI ArcGIS software and a module, such as our recently developed ArcGIS extension 3DLT (laser tool), a simple yet sophisticated platform exists for mapping, visualizing, and analyzing outcrops in real time in the field. The potential of laser mapping is demonstrated. in the Paleozoic outcrops of a structural geology teaching site in the Stick Hills, Oklahoma. Fast laser scanning and digital photography are used to build a 3D photorealistic model of an area of the anticline. The 3DLT is used for mapping specific detailed features such as contacts and faults. Three-dimensional quantitative information can be extracted from the geology with these methods. A laser rangefinder combined with 3DLT can image and display terrain and outcrop features in the field, in real time. Mapping with fast scanners requires several steps in processing of the point cloud data utilizing a variety of sophisticated and expensive software, but can capture an entire outcrop, such as a mountainside. The resulting model then can be analyzed in the lab. When combined with digital photography, virtual photorealistic models derived from point clouds can be even more effectively analyzed. The most appropriate method for digitally mapping geology depends on a variety of issues, such as cost, time, complexity, portability, and the project goals. © 2007 Geological Society of America.