Quantifying discontinuity orientation and persistence on high mountain rock slopes and large landslides using terrestrial remote sensing techniques

This paper describes experience gained in the application of terrestrial digital photogrammetry and terrestrial laser scanning for the characterization of the structure of high mountain rock slopes and large landslides. A methodology allowing the creation and registration of 3-D models with limited access to high mountain rock slopes is developed and its accuracy verified. The importance of occlusion, ground resolution, scale and reflectivity are discussed. Special emphasis is given to the concept of observation scale and resulting scale bias and its influence on discontinuity characterization. The step-path geometry of persistent composite surfaces and its role in remote sensing measurements are described. An example of combined terrestrial digital photogrammetry and terrestrial laser scanning applied in the generation of a 3-D model of the South Peak of Turtle Mountain, the location of the Frank Slide, is presented. The advantages gained from the combined use of these techniques and the potential offered through long-range terrestrial digital photogrammetry, using high focal length lenses up to 400 mm is illustrated. Special emphasis is given to the potential of this specific technique, which has to the authors knowledge rarely been documented in the geotechnical literature.