Reliability and Uncertainties of the Analysis of an Unstable Rock Slope Performed on RPAS Digital Outcrop Models: The Case of the Gallivaggio Landslide (Western Alps, Italy)

Menegoni, Niccolò; Giordan, Daniele; Perotti, Cesare

doi:10.3390/rs12101635

Cited by 34 publications

(16 citation statements)

References 38 publications

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“…For this reason, SfM can be considered a good solution for the acquisition of the 3D model of natural caves, where the use of more complex topographic instruments can be complicated (in several cases nearly impossible). Starting from the experience using the SfM approach in different environments (e.g., [6,[61][62][63]), we defined and tested a methodology dedicated to the survey of natural caves for their 3D modeling at different scales.…”

Section: Development Of a Methodology For The Acquisition Of A 3d Model Of A Natural Cavementioning

confidence: 99%

Survey Solutions for 3D Acquisition and Representation of Artificial and Natural Caves

et al. 2021

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A three-dimensional survey of natural caves is often a difficult task due to the roughness of the investigated area and the problems of accessibility. Traditional adopted techniques allow a simplified acquisition of the topography of caves characterized by an oversimplification of the geometry. Nowadays, the advent of LiDAR and Structure from Motion applications eased three-dimensional surveys in different environments. In this paper, we present a comparison between other three-dimensional survey systems, namely a Terrestrial Laser Scanner, a SLAM-based portable instrument, and a commercial photo camera, to test their possible deployment in natural caves survey. We presented a comparative test carried out in a tunnel stretch to calibrate the instrumentation on a benchmark site. The choice of the site is motivated by its regular geometry and easy accessibility. According to the result obtained in the calibration site, we presented a methodology, based on the Structure from Motion approach that resulted in the best compromise among accuracy, feasibility, and cost-effectiveness, that could be adopted for the three-dimensional survey of complex natural caves using a sequence of images and the structure from motion algorithm. The methods consider two different approaches to obtain a low resolution complete three-dimensional model of the cave and ultra-detailed models of most peculiar cave morphological elements. The proposed system was tested in the Gazzano Cave (Piemonte region, Northwestern Italy). The obtained result is a three-dimensional model of the cave at low resolution due to the site’s extension and the remarkable amount of data. Additionally, a peculiar speleothem, i.e., a stalagmite, in the cave was surveyed at high resolution to test the proposed high-resolution approach on a single object. The benchmark and the cave trials allowed a better definition of the instrumentation choice for underground surveys regarding accuracy and feasibility.

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Section: Development Of a Methodology For The Acquisition Of A 3d Model Of A Natural Cavementioning

confidence: 99%

Survey Solutions for 3D Acquisition and Representation of Artificial and Natural Caves

et al. 2021

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“…The discontinuities considered by the ROKA calculation were mapped manually onto the 3D point cloud through the CloudCompare software (with the methodology described in [23,44,45]. This methodology consists of selecting the points onto the 3D model representing the discontinuity traces and planes and then estimating the orientation of their best-fit plane.…”

Section: Case A: Northern Apennines-calcareous Turbiditesmentioning

confidence: 99%

An Open-Source Algorithm for 3D ROck Slope Kinematic Analysis (ROKA)

2021

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The Markland test is one of the most diffused and adopted methods of kinematic analysis for the identification of critical intersections of rock discontinuities that could generate rock failures. Traditionally, the kinematic analysis is based on the use of a stereographic approach that is able to identify the critical combination between the orientations of discontinuities and the rock wall. The recent improvements in the use of Digital Outcrop Models (DOMs) created the conditions for the development of a new automatized approach. We present ROck Slope Kinematic Analysis (ROKA) which is an open-source algorithm aimed at performing the Kinematic Analysis using the discontinuity measures collected onto a 3D DOM. The presented algorithm is able to make a local identification of the possible critical combination between the identified discontinuities and the orientation of the slope. Using this approach, the algorithm is able to identify on the slope the presence of critical combinations according to the traditional kinematic analysis of planar failure, flexural toppling, wedge failure, and direct toppling modes of failures and then visualize them on DOMs. In this way, the traditional approach is more effective and can be adopted for a more detailed analysis of large and complex areas.

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“…The latter was relevant in a few specific zones; discontinuities with potential risk can be present therein. Discontinuities identified by automatic approaches such as those used here need careful validation, since the software can erroneously identify flat features as discontinuities, divide discontinuities in smaller planes, and may fail to detect discontinuities perpendicular to the slope face [55]. This may occur in the set of discontinuities obtained for facadenadir pictures with Discontinuity Set Extraction software.…”

Section: Use Of Detailed Topographies In Monitoring Mining Highwallsmentioning

confidence: 99%

“…However, AMSL topographies cannot detect many of them (Figures 8 and 11), supporting the main objective of this study of attaining the best drone setting to obtain topographies of high accuracy and point cloud density for stability analyses. An SfM-UAV survey without control points can be used to identify discontinuities [55]; however, such a topography does not allow precise measurement of displacements between multitemporal surveys. A high correlation between discontinuities detected with the software Discontinuity Set Extraction and those manually mapped can be attained.…”

Section: Use Of Detailed Topographies In Monitoring Mining Highwallsmentioning

confidence: 99%

Improvement of Workflow for Topographic Surveys in Long Highwalls of Open Pit Mines with an Unmanned Aerial Vehicle and Structure from Motion

et al. 2021

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Conducting topographic surveys in active mines is challenging due ongoing operations and hazards, particularly in highwalls subject to constant and active mass movements (rock and earth falls, slides and flows). These vertical and long surfaces are the core of most mines, as the mineral feeding mining production originates there. They often lack easy and safe access paths. This framework highlights the importance of accomplishing non-contact high-accuracy and detailed topographies to detect instabilities prior to their occurrence. We have conducted drone flights in search of the best settings in terms of altitude mode and camera angle, to produce digital representation of topographies using Structure from Motion. Identification of discontinuities was evaluated, as they are a reliable indicator of potential failure areas. Natural shapes were used as control/check points and were surveyed using a robotic total station with a coaxial camera. The study was conducted in an active kaolin mine near the Alto Tajo Natural Park of East-Central Spain. Here the 140 m highwall is formed by layers of limestone, marls and sands. We demonstrate that for this vertical landscape, a facade drone flight mode combined with a nadir camera angle, and automatically programmed with a computer-based mission planning software, provides the most accurate and detailed topographies, in the shortest time and with increased flight safety. Contrary to previous reports, adding oblique images does not improve accuracy for this configuration. Moreover, neither extra sets of images nor an expert pilot are required. These topographies allowed the detection of 93.5% more discontinuities than the Above Mean Sea Level surveys, the common approach used in mining areas. Our findings improve the present SfM-UAV survey workflows in long highwalls. The versatile topographies are useful for the management and stabilization of highwalls during phases of operation, as well closure-reclamation.

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Reliability and Uncertainties of the Analysis of an Unstable Rock Slope Performed on RPAS Digital Outcrop Models: The Case of the Gallivaggio Landslide (Western Alps, Italy)

Cited by 34 publications

References 38 publications

Survey Solutions for 3D Acquisition and Representation of Artificial and Natural Caves

Survey Solutions for 3D Acquisition and Representation of Artificial and Natural Caves

An Open-Source Algorithm for 3D ROck Slope Kinematic Analysis (ROKA)

Improvement of Workflow for Topographic Surveys in Long Highwalls of Open Pit Mines with an Unmanned Aerial Vehicle and Structure from Motion

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