Rockfall trajectory reconstruction: a flexible method utilizing video footage and high-resolution terrain models

[摘要] Many examples of rockfall simulation software provide greatflexibility to the user at the expense of a hardly achievable parameterunification. With sensitive site-dependent parameters that are hardlygeneralizable from the literature and case studies, the user must properlycalibrate simulations for the desired site by performing back-calculationanalyses. Thus, rockfall trajectory reconstruction methods are needed. Forthat purpose, a computer-assisted videogrammetric 3D trajectoryreconstruction method (CAVR) built on earlier approaches is proposed.Rockfall impacts are visually identified and timed from video footage andare manually transposed on detailed high-resolution 3D terrain models thatact as the spatial reference. This shift in reference removes the dependencyon steady and precisely positioned cameras, ensuring that the CAVR methodcan be used for reconstructing trajectories from witnessed previous recordswith nonoptimal video footage. For validation, the method is applied toreconstruct some trajectories from a rockfall experiment performed by theWSL Institute for Snow and Avalanche Research SLF. The results are comparedto previous ones from the SLF and share many similarities. Indeed, thetranslational energies, bounce heights, rotational energies, and impactpositions against a flexible barrier compare well with those from the SLF.The comparison shows that the presented cost-effective and flexible CAVRmethod can reproduce proper 3D rockfall trajectories from experiments orreal rockfall events.

[学科分类] 土壤学