Integration of laser scanning and thermal imaging in monitoring optimization and assessment of rockfall hazard: a case history in the Carnic Alps (Northeastern Italy)

2014 ◽  
Vol 76 (3) ◽  
pp. 1535-1549 ◽  
Author(s):  
Giordano Teza ◽  
Gianluca Marcato ◽  
Alessandro Pasuto ◽  
Antonio Galgaro
Keyword(s):  
Case History ◽  
Thermal Imaging ◽  
Laser Scanning ◽  
Carnic Alps ◽  
Rockfall Hazard ◽  
Northeastern Italy

scholarly journals Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling

2018 ◽  
Vol 18 (2) ◽  
pp. 583-597 ◽  
Author(s):  
Ákos Török ◽  
Árpád Barsi ◽  
Gyula Bögöly ◽  
Tamás Lovas ◽  
Árpád Somogyi ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Cross Sections ◽  
Laser Scanning ◽  
Digital Terrain Model ◽  
Field Measurements ◽  
Satellite System ◽  
Surface Model ◽  
Rockfall Hazard ◽  
Terrain Model ◽  
Remote Sensing Techniques

Abstract. Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System) was used to collect images which were processed by Pix4D mapper (structure from motion technology) to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS) with the use of seven ground control points. The obtained digital surface model (DSM) was processed (vegetation removal) and the derived digital terrain model (DTM) allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method). Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE–WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS).

scholarly journals WATER LEAKAGE DIAGNOSIS IN METRO TUNNELS BY INTERGRATION OF LASER POINT CLOUD AND INFRARED THERMAL IMAGING

2018 ◽  
Vol XLII-3 ◽  
pp. 2167-2171
Author(s):  
P. Yu ◽  
H. Wu ◽  
C. Liu ◽  
Z. Xu
Keyword(s):  
Distance Function ◽  
Thermal Imaging ◽  
Point Cloud ◽  
Laser Scanning ◽  
Water Leakage ◽  
Infrared Thermal Imaging ◽  
Centroid Distance ◽  
Metro Tunnel ◽  
Infrared Thermal Images ◽  
Centroid Distance Function

Diagnosis of water leakage in metro tunnels is of great significance to the metro tunnel construction and the safety of metro operation. A method that integrates laser scanning and infrared thermal imaging is proposed for the diagnosis of water leakage. The diagnosis of water leakage in this paper is mainly divided into two parts: extraction of water leakage geometry information and extraction of water leakage attribute information. Firstly, the suspected water leakage is obtained by threshold segmentation based on the point cloud of tunnel. And the real water leakage is obtained by the auxiliary interpretation of infrared thermal images. Then, the characteristic of isotherm outline is expressed by solving Centroid Distance Function to determine the type of water leakage. Similarly, the location of leakage silt and the direction of crack are calculated by finding coordinates of feature points on Centroid Distance Function. Finally, a metro tunnel part in Shanghai was selected as the case area to make experiment and the result shown that the proposed method in this paper can be used to diagnosis water leakage disease completely and accurately.

Laser-Thermal Imaging

2010 ◽  
Author(s):  
R. Aaron Falk ◽  
Tram Pham
Keyword(s):  
Thermal Imaging ◽  
Laser Scanning ◽  
Raman Laser ◽  
Diffraction Limit ◽  
Power Scaling ◽  
Scanning Microscope ◽  
Laser Scanning Microscope ◽  
Near Ir ◽  
Linear Effects ◽  
Exponential Power

Abstract Laser induced emission and photocurrents with exponential power scaling were discovered using a near IR Raman laser scanning microscope. The potential for utilizing these highly non-linear effects for sub-diffraction limited imaging has been explored both theoretically and experimentally. A three-fold improvement over the linear diffraction limit was predicted and experimentally validated.

scholarly journals Detection of rock bridges by infrared thermal imaging and modeling

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Antoine Guerin ◽  
Michel Jaboyedoff ◽  
Brian D. Collins ◽  
Marc-Henri Derron ◽  
Greg M. Stock ◽  
...  
Keyword(s):  
Thermal Imaging ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Intact Rock ◽  
Infrared Thermal Imaging ◽  
Rockfall Hazard ◽  
Small Areas ◽  
Rock Bridges ◽  
Ground Based Lidar ◽  
The Stability

Abstract Characterization of rock discontinuities and rock bridges is required to define stability conditions of fractured rock masses in both natural and engineered environments. Although remote sensing methods for mapping discontinuities have improved in recent years, remote detection of intact rock bridges on cliff faces remains challenging, with their existence typically confirmed only after failure. In steep exfoliating cliffs, such as El Capitan in Yosemite Valley (California, USA), rockfalls mainly occur along cliff-parallel exfoliation joints, with rock bridges playing a key role in the stability of partially detached exfoliation sheets. We employed infrared thermal imaging (i.e., thermography) as a new means of detecting intact rock bridges prior to failure. An infrared thermal panorama of El Capitan revealed cold thermal signatures for the surfaces of two granitic exfoliation sheets, consistent with the expectation that air circulation cools the back of the partially detached sheets. However, we also noted small areas of warm thermal anomalies on these same sheets, even during periods of nocturnal rock cooling. Rock attachment via rock bridges is the likely cause for the warm anomalies in the thermal data. 2-D model simulations of the thermal behavior of one of  the monitored sheets reproduce the observed anomalies and explain the temperature differences detected in the rock bridge area. Based on combined thermal and ground-based lidar imaging, and using geometric and rock fracture mechanics analysis, we are able to quantify the stability of both sheets. Our analysis demonstrates that thermography can remotely detect intact rock bridges and thereby greatly improve rockfall hazard assessment.

scholarly journals 3D HAZARD ANALYSIS AND OBJECT-BASED CHARACTERIZATION OF LANDSLIDE MOTION MECHANISM USING UAV IMAGERY

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 425-430 ◽  
Author(s):  
E. Karantanellis ◽  
V. Marinos ◽  
E. Vassilakis
Keyword(s):  
Surface Morphology ◽  
Road Network ◽  
Laser Scanning ◽  
Complex Surface ◽  
Point Clouds ◽  
High Mountain ◽  
Semantic Classification ◽  
Rockfall Hazard ◽  
3D Point Clouds ◽  
Object Based

<p><strong>Abstract.</strong> Late years, innovative close-range remote sensing technology such as Unmanned Aerial Vehicle (UAV) photogrammetry and Terrestrial Laser Scanning (TLS) are widely applied in the field of geoscience due to their efficiency in collecting data about surface morphology. Their main advantage stands on the fact that conventional methods are mainly collecting point measurements such as compass measurements of bedding and fracture orientation solely from accessible areas. The current research aims to demonstrate the applicability of UAVs in managing landslide and rockfall hazard in mountainous environments during emergency situations using object-based approach. Specifically, a detailed UAV survey took place in a test site namely as Proussos, one of the most visited and famous Monasteries in the territory of Evritania prefecture, in central Greece. An unstable steep slope across the sole road network results in continuous failures and road cuts after heavy rainfall events. Structure from Motion (SfM) photogrammetry is used to provide detailed 3D point clouds describing the surface morphology of landslide objects. The latter resulted from an object-based classification approach of the photogrammetric point cloud products into homogeneous and spatially connected elements. In specific, a knowledge-based ruleset has been developed in accordance with the local morphometric parameters. Orthomosaic and DSM were segmented in meaningful objects based on a number of geometrical and contextual properties and classified as a landslide object (scarp, depletion zone, accumulation zone). The resulted models were used to detect and characterize 3D landslide features and provide a hazard assessment in respect to the road network. Moreover, a detailed assessment of the identified failure mechanism has been provided. The proposed study presents the effectiveness and efficiency of UAV platforms to acquire accurate photogrammetric datasets from high-mountain environments and complex surface topographies and provide a holistic object-based framework to characterize the failure site based on semantic classification of the landslide objects.</p>

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