Assessing the Capabilities and Limitation of Terrestrial LiDAR, Terrestrial Photogrammetry, and Airborne LiDAR for Mapping Differential Slope Changes

摘要

Assessing transportation corridors exposed to the hazard of rockfalls and rockslides traditionally involves mapping and measuring physical characteristic of the visible cut or natural slope face. These assessment systems rely on the ability to visually identify the source zone, and determine the possibility of it releasing material and affecting the corridor. Conducting this form of traditional rockfall hazard analysis is extremely challenging in mountainous terrain where site accessibility is often limited, visibility is obstructed or minimal, and the terrain is extremely complex. Advancements in remote sensing technology and processing capabilities have enabled engineers to obtain valuable 3-Dimensional (3D) information in mountainous terrain that directly facilitates the understanding of the physical environment. Using 3D remote sensing data collected at different points in time enables the monitoring of differential slope change processes, which can be used to track rockfall frequency and magnitude. This information can be critical in assessing a transportation corridor for risk from natural threats. Various remote sensing technologies are capable of generating data suitable for differential change analysis, including terrestrial LiDAR, terrestrial photogrammetry, and airborne LiDAR. However, the advantages and limitations of these technologies and when they should optimally be deployed is not widely published or clearly defined. Between December 2012 and December 2013 the efficacy of three remote sensing technologies: terrestrial and aerial LiDAR, and gigapixel photogrammetry, were compared for detecting natural and anthropogenic changes at a location along the CN railway, in British Columbia, Canada. The results demonstrate a high degree of interoperability between the different technologies, the ability to map topographical change with all three technologies, and the limitations/weaknesses of each technology with respect to mapping change. These results will aid decision-making with respect to implementation of remote sensing technologies to monitor changes to rock slopes transportation corridors, which would lead to better hazard assessments.