Climate change and cryosphere in high mountains: updates from the Capanna Margherita hut study case (Punta Gnifetti, Monte Rosa Massif, Pennine Alps)

2021 ◽  
Author(s):  
Marco Giardino ◽  
Antonio Montani ◽  
Andrea Tamburini ◽  
Francesco Calvetti ◽  
Davide Martelli ◽  
...  
Keyword(s):  
Climate Change ◽  
Rock Mass ◽  
Point Cloud ◽  
Temporal Stability ◽  
Laser Scanner ◽  
Monitoring Network ◽  
Terrestrial Laser Scanner ◽  
Mountain Glaciers ◽  
3D Numerical Modelling ◽  
Monte Rosa

<p>Mountain glaciers and permafrost are among the most evident geomorphological tracers of climate change. In the last decades, they showed a growing and faster response also at very high elevations, leading to increased instability of the Alpine landscape. In the meanwhile, they became of great interest also for their possible interactions with human activities and infrastuctures.</p><p>On the highest massif of the Alps, as for example the Monte Rosa, this interaction is mainly represent by the one with mountaineering activities. The top of Gnifetti Peak (4554 m a.s.l.), with the Capanna Margherita hut (the highest in Europe), is under investigation to better understand the effects of global warming on hut stability and mountaineering routes safety. Thanks to the cooperation between the Italian Alpine Club (CAI), University of Turin (UniTo), Politecnico di Milano (PoliMi) and IMAGEO srl, a first assessment of geological and glacial settings of hut surroundings have been performed on 2019. Data collection continued on 2020, by means of comparative analyses designated to: a) identify the relevant geomechanical features for rock mass stability; b) verify permafrost related instabilities; c) reconstruct the ice-covered morphology of the Punta Gnifetti peak; d) calculate rock-building interactions. Here below the related results:</p><p>1) A 3D model of the area has been obtained by integrating helicopter-borne photogrammetry with terrestrial laser scanner surveys.</p><p>2) Glacier thickness at the Colle Gnifetti has been established thanks to GPR survey.</p><p>3) From the comparison of a large number of historical pictures a first multi-temporal stability analysis highlighted sector of greater instability. Results of this work are freely available on the website www.geositlab.unito.it/capanna .</p><p>4) The geomechanical features of the rock mass below and around the hut have been retrieved from the analysis of the dense point cloud provided by terrestrial laser scanner integrated with direct field investigations.</p><p>5) Constructive drawing of the hut have been obtained from the terrestrial laser scanner point cloud integrated with manual measurements taken inside the structure.</p><p>6) 3D numerical modelling are going to be applied in order to simulate the interactions between the hut and the foundation rock on the base of the above data.</p><p>The ongoing activities are addressed to a detailed study of more vulnerable sectors of the Punta Gnifetti to better understand morphodynamics and possible interactions with mountaineering activities. This will be performed through a two-way investigation. On one hand, a link with alpine guides and mountain hut keepers has been established, in order to have “sentries” ready to report instabilities and detect new hazards and risks. On the other hand, a monitoring network will be installed around Capanna Margherita in order to collect data on weather, glacier and permafrost conditions.</p>

scholarly journals Fitting Terrestrial Laser Scanner Point Clouds with T-Splines: Local Refinement Strategy for Rigid Body Motion

2021 ◽  
Vol 13 (13) ◽  
pp. 2494
Author(s):  
Gaël Kermarrec ◽  
Niklas Schild ◽  
Jan Hartmann
Keyword(s):  
Point Cloud ◽  
Goodness Of Fit ◽  
Laser Scanner ◽  
Point Clouds ◽  
Statistical Testing ◽  
Computational Time ◽  
Terrestrial Laser Scanner ◽  
Reference Surface ◽  
Local Refinement ◽  
Surface Approximation

T-splines have recently been introduced to represent objects of arbitrary shapes using a smaller number of control points than the conventional non-uniform rational B-splines (NURBS) or B-spline representatizons in computer-aided design, computer graphics and reverse engineering. They are flexible in representing complex surface shapes and economic in terms of parameters as they enable local refinement. This property is a great advantage when dense, scattered and noisy point clouds are approximated using least squares fitting, such as those from a terrestrial laser scanner (TLS). Unfortunately, when it comes to assessing the goodness of fit of the surface approximation with a real dataset, only a noisy point cloud can be approximated: (i) a low root mean squared error (RMSE) can be linked with an overfitting, i.e., a fitting of the noise, and should be correspondingly avoided, and (ii) a high RMSE is synonymous with a lack of details. To address the challenge of judging the approximation, the reference surface should be entirely known: this can be solved by printing a mathematically defined T-splines reference surface in three dimensions (3D) and modeling the artefacts induced by the 3D printing. Once scanned under different configurations, it is possible to assess the goodness of fit of the approximation for a noisy and potentially gappy point cloud and compare it with the traditional but less flexible NURBS. The advantages of T-splines local refinement open the door for further applications within a geodetic context such as rigorous statistical testing of deformation. Two different scans from a slightly deformed object were approximated; we found that more than 40% of the computational time could be saved without affecting the goodness of fit of the surface approximation by using the same mesh for the two epochs.

scholarly journals Comparison of Depth Camera and Terrestrial Laser Scanner in Monitoring Structural Deflections

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 201
Author(s):  
Michael Bekele Maru ◽  
Donghwan Lee ◽  
Kassahun Demissie Tola ◽  
Seunghee Park
Keyword(s):  
Optical Sensors ◽  
Point Cloud ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Point Clouds ◽  
Depth Camera ◽  
Terrestrial Laser Scanner ◽  
Cloud Data ◽  
3D Point Clouds ◽  
3D Information

Modeling a structure in the virtual world using three-dimensional (3D) information enhances our understanding, while also aiding in the visualization, of how a structure reacts to any disturbance. Generally, 3D point clouds are used for determining structural behavioral changes. Light detection and ranging (LiDAR) is one of the crucial ways by which a 3D point cloud dataset can be generated. Additionally, 3D cameras are commonly used to develop a point cloud containing many points on the external surface of an object around it. The main objective of this study was to compare the performance of optical sensors, namely a depth camera (DC) and terrestrial laser scanner (TLS) in estimating structural deflection. We also utilized bilateral filtering techniques, which are commonly used in image processing, on the point cloud data for enhancing their accuracy and increasing the application prospects of these sensors in structure health monitoring. The results from these sensors were validated by comparing them with the outputs from a linear variable differential transformer sensor, which was mounted on the beam during an indoor experiment. The results showed that the datasets obtained from both the sensors were acceptable for nominal deflections of 3 mm and above because the error range was less than ±10%. However, the result obtained from the TLS were better than those obtained from the DC.

scholarly journals Interactive Trunk Extraction from Forest Point Cloud

2014 ◽  
Vol XL-5 ◽  
pp. 433-436
Author(s):  
T. Mizoguchi ◽  
Y. Kobayashi
Keyword(s):  
Forest Management ◽  
Point Cloud ◽  
Laser Scanner ◽  
Interactive System ◽  
Terrestrial Laser Scanner ◽  
Diameter At Breast Height ◽  
Breast Height

For forest management or monitoring, it is required to constantly measure several parameters of each tree, such as height, diameter at breast height, and trunk volume. Terrestrial laser scanner has been used for this purpose instead of human workers to reduce time and cost for the measurement. In order to use point cloud captured by terrestrial laser scanner in the above applications, it is an important step to extract all trees or their trunks separately. For this purpose, we propose an interactive system in which a user can intuitively and efficiently extract each trunk by a simple editing on the distance image created from the point cloud. We demonstrate the effectiveness of our proposed system from various experiments.

scholarly journals Accuracy Analysis Of Three Dimensional Models Of Building Prof. H. Soedarto S. H. Using The Terrestrial Laser Scanner Technology Based On Traverse Method

Teknik ◽  
2019 ◽  
Vol 39 (2) ◽  
pp. 94
Author(s):  
Yudo Prasetyo
Keyword(s):  
Point Cloud ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Terrestrial Laser Scanner ◽  
Accuracy Analysis ◽  
Dimensional Models ◽  
Data Point ◽  
Three Dimensional Models

Teknologi dokumentasi gedung secara spasial untuk konservasi dan perencanaan tata ruang semakin berkembang pesat. Urgensi tingkat ketelitian dalam suatu pengukuran juga dituntut semakin tinggi. Salah satu teknologi pembentukan objek tiga dimensi yang berkembang saat ini adalah Terrestrial Laser Scanner (TLS). Metode pengukuran TLS terdiri atas 4 metode yaitu: Cloud to Cloud, Target to Target, Traverse, dan metode kombinasi. Penelitian ini bertujuan untuk menganalisa tingkat ketelitian metode Traverse dalam pengukuran suatu objek model tiga dimensi untuk keperluan dokumentasi gedung menggunakan TLS.Ketelitian metode Traverse akan diujikan pada Gedung Prof. H. Soedarto, S. H. Tingkat ketelitiannya diujikan pada dua parameter yakni hasil metode registrasi dan hasil visualisasi model tiga dimensi. Hasil analisis pengolahan data point cloud menunjukkan bahwa alat TLS dengan metode Traverse dapat digunakan untuk menghasilkan model tiga dimensi Gedung Prof. Sudarto, S. H. Nilai rata-rata validasi yang diperoleh adalah sebesar 0,004 meter dengan besaran ketelitian model RMSE sebesar ±0,00611 meter. 

Climate change and cryosphere in high mountains: preliminary results of field monitoring at Capanna Margherita hut, Punta Gnifetti (Monte Rosa, Pennine Alps)

2020 ◽  
Author(s):  
Marco Giardino ◽  
Antonio Montani ◽  
Andrea Tamburini ◽  
Francesco Calvetti ◽  
Alessandro Borghi ◽  
...  
Keyword(s):  
Climate Change ◽  
Rock Mass ◽  
Permafrost Degradation ◽  
High Mountains ◽  
Cooperative Research ◽  
Preliminary Results ◽  
Climate Change Effects ◽  
Meteorological Observatory ◽  
Historical Series ◽  
Monte Rosa

<p>In the last decades, climate change effects are spreading on cryosphere of mid latitude high mountains, affecting all environmental and territorial components. The Italian Alpine Club (CAI) is a privileged institution for observing climate change effects on cryosphere in high mountains, as well as for supporting scientists to proper assessment studies of related natural hazards, exposure, vulnerability effects, particularly those around alpine refuges and access routes. CAI has started a cooperative research with University of Torino (UniTO), Politecnico of Milano (PoliMI) and IMAGEO srl, focused in deglaciation, permafrost degradation and slope instabilities at the Punta Gnifetti peak (“Signal Kuppe, 4554 m a.s.l.), Monte Rosa (Pennine Alps, border between Italy and Switzerland). Here is the Margherita Hut, the highest refuge in Europe and a physical-meteorological observatory, as well as home to medical and scientific UniTO laboratories.</p><p>Activities started on May 2019 with a retrospective collection and interpretation of photos and archival news on the Punta Gnifetti environment. Multi-temporal geomorphological settings are compared to meteorological historical series for creating a morphoclimatic "timeline".</p><p>Instrumental monitoring and in situ field work began on August 2019, including: 1) determination of the ice thickness of the glacial cover by using georadar; 2) characterization of the geomechanical structure of the rock mass by means of terrestrial laser scanner; 3) establishment of a topographical reference point and georeferencing of all measuring points; 4) collection of litho-structural and geomorphological data for a reference geological model of the Punta Gnifetti; 5) photogrammetric helicopter flight for the 3D reconstruction of the site; 6) direct measurements of internal areas in order to obtain as-built building plans; 7) assessment of building services.</p><p>Preliminary results are presented here, together with directions for an effective data collection to be continued on 2020, including comparative analyses designated to: a) identify the relevant geomechanical features for rock mass stability; b) verify presence of ice inside fractures; c) reconstruct the ice-covered morphology of the Punta Gnifetti peak.</p>

scholarly journals CALIBRATION AND STABILITY ANALYSIS OF THE VLP-16 LASER SCANNER

2016 ◽  
Vol XL-3/W4 ◽  
pp. 55-60 ◽  
Author(s):  
C. L. Glennie ◽  
A. Kusari ◽  
A. Facchin
Keyword(s):  
Stability Analysis ◽  
Point Cloud ◽  
Temporal Stability ◽  
Laser Scanner ◽  
Effect Of Temperature ◽  
Geometric Calibration ◽  
Long Term Stability ◽  
The Individual

We report on a calibration and stability analysis of the Velodyne VLP-16 LiDAR scanner. The sensor is evaluated for long-term stability, geometric calibration and the effect of temperature variations. To generalize the results, three separate VLP-16 sensors were examined. The results and conclusions from the analysis of each of the individual sensors was similar. We found that the VLP-16 showed a consistent level of performance, in terms of range bias and noise level over the tested temperature range from 0–40 °C. A geometric calibration was able to marginally improve the accuracy of the VLP-16 point cloud (by approximately 20%) for a single collection, however the temporal stability of the geometric calibration negated this accuracy improvement. Overall, it was found that there is some long-term walk in the ranging observations from individual lasers within the VLP-16, which likely causes the instability in the determination of geometric calibration parameters. However, despite this range walk, the point cloud delivered from the VLP-16 sensors tested showed an accuracy level within the manufacturer specifications of 3 cm RMSE, with an overall estimated RMSE of range residuals between 22 mm and 27 mm.

Structure Deformation Measurement with Terrestrial Laser Scanner at Pathein Bridge in Myanmar

2018 ◽  
Vol 13 (1) ◽  
pp. 40-49 ◽  
Author(s):  
Nuntikorn Kitratporn ◽  
◽  
Wataru Takeuchi ◽  
Koji Matsumoto ◽  
Kohei Nagai
Keyword(s):  
Point Cloud ◽  
Cloud Model ◽  
Laser Scanner ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Terrestrial Laser Scanner ◽  
Bridge Structure ◽  
Surface Geometry ◽  
Deformation State ◽  
Measurement Results

In Myanmar, defects and possible deformation were reported in many long-span suspension bridges. The current state of bridge infrastructure must be inspected, so that deterioration can be stalled and failure can be prevented. A 3D laser scanner, specifically the terrestrial laser scanner (TLS), has demonstrated the ability to capture surface geometry with millimeter accuracy. Consequently, TLS technology has received significant interest in various applications including in the field of structural survey. However, research on its application in large bridge structure remains limited. This study examines the use of TLS point cloud for the measurement of three deformation behaviors at the Pathein Suspension Bridge in Myanmar. These behaviors include tower inclination, hanger inclination, and deflection of bridge truss. The measurement results clearly captured the deformation state of the bridge. A comparison of the measurement results with available conventional measurements yielded overall agreement. However, errors were observed in some areas, which could be due to noise and occlusion in the point cloud model. In this study, the advantages of TLS in providing non-discrete data, direct measurement in meaningful unit, and access to difficult-to-access sections, such as top of towers or main cables, were demonstrated. The limitations of TLS as observed in this study were mainly influenced by external factors during field survey. Hence, it was suggested that further study on appropriate TLS surveying practice for large bridge structure should be conducted.

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