PAPER MAPPING IS DEAD AND FLAT MAP GEOLOGIC ANALYSIS HAS ONE FOOT IN THE GRAVE: THE NEW REVOLUTION IN THREE DIMENSIONAL STRUCTURAL ANALYSIS USING INEXPENSIVE TERRAIN MODELS AND VISUALIZATION SOFTWARE

Two hundred years ago Smith’s geologic map changed the world, yet flat-map representations of a 3D world remain a problem for visualization of 3D geology in any area that is not flatter than Kansas. We are in a new age, however, when 2D map reading skills are becoming archaic and akin to using a plane table and alidade 40 years ago. Integral to this change is the combination of digital mapping on increasingly sophisticated mobile computers and “structure from motion” based photogrammetry, which allows inexpensive production of high resolution 3D terrain models as base maps. The latter is truly transformative in that 1-2 people can generate a georeferenced, high-resolution, photorealistic 3D terrain model comparable to Terrestrial Lidar with less than $1,000 worth of equipment in less field time/effort than LiDAR acquisition. Use of an inexpensive drone can further streamline that field effort. It is difficult to overemphasize the potential impact of this technology on the future of all field sciences, but field geology in particular. Inaccessible cliff faces can now be rendered in high-resolution 3D for geologic mapping; the technology affords mind-boggling detailed mapping in 3D with resolution to a few cm; and even in areas with poor outcrop ALL key outcrops can be recorded as 3D objects embedded in a spatial database for better documentation of structure. The possibilities are nearly limitless and we have only begun to scratch the surface of what is possible. Although this technology is revolutionizing field geology, it is not yet routine. We have found several pitfalls and technology issues that force alternative workflows, and these workflows will need to be modified continually as technology advances. Most issues are in software with no single application perfect for this work but limitations of mobile hardware are also important. Nonetheless, the problems remain trivial compared to flat-map problems in areas of steep terrain and are acceptable for routine work. Presently, a two-phase field procedure is required that begins with a data acquisition phase with preliminary interpretations on the terrain model followed by a second field session to finalize interpretations. Limitations aside, these technologies put geology at the dawn of a new revolution in field studies that may be comparable to Smith’s first map.