Papers by Raphael Antoine
Http Www Theses Fr, 2009
Introduction Générale Chapitre 2. Volcanisme du Piton de La Fournaise et de Cerberus (Mars) Agèt ... more Introduction Générale Chapitre 2. Volcanisme du Piton de La Fournaise et de Cerberus (Mars) Agèt agèt... Lasab lé an san La mèr lé rouz Lo san la racine volkan I fé nir la mèr rouz...
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
In this paper, we present a methodology to fusion 3D visible and thermal infrared (TIR) informati... more In this paper, we present a methodology to fusion 3D visible and thermal infrared (TIR) information on a coastal landslide area located in Normandy, France. A reflex and TIR camera onboard an Unmanned Aerial Vehicle are utilized to generate a 3D visible and a thermal model using Photogrammetry. A Pythonwritten algorithm is then used to associate the thermal scalar on the TIR model to the closest point on the visible point cloud, before applying α-blending to ease the visualization of both data sets. This methodology leads to the generation of an integrated 3D thermo-visible model, allowing the direct analysis of the surface temperatures, visible data and geometric configuration of the landslide.
Saltwater wedge is a natural phenomenon defined as the displacement and retention of saltwater in... more Saltwater wedge is a natural phenomenon defined as the displacement and retention of saltwater in a freshwater aquifer. This saline intrusion can modify the content of dissolved elements in coastal freshwater aquifers, which can have consequences for water use (drinking or agricultural), on the ecology, the environment, the erosion of coasts, and the stability of coastal structures.This study focuses on the integration and coupled interpretation of various geophysical and optical data obtained on the ground and by drone to evaluate the intrusion of seawater in a coastal chalk cliff in Sainte-Marguerite-sur-Mer in Normandy, France. The objective is to characterize the freshwater-saltwater interface and describe the internal structure of the formation. To do so, the combination of geophysical (Electrical Resistivity Imaging, ERI), aerial (visible and thermal infrared photogrammetry, IRT), and geotechnical (piezometers) methods was adopted.The ten ERI profiles (transverse and longitudi...
HAL (Le Centre pour la Communication Scientifique Directe), 2013
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
In this work, the main goal is to study the evolution of the coastline at a local scale, and to g... more In this work, the main goal is to study the evolution of the coastline at a local scale, and to get a better understanding of the erosion process. We propose a methodology based on a new software (PyMERI) in order to build a 3D mesh of the subsoil from a Digital Elevation Model (DEM) on which a Partial Differential Equation-direct problem-allowing to recover the voltage (electrical field) in the ground is solved yielding numerical simulations of Electrical Resistivity Imaging (ERI). This study is complemented by the resolution of an inverse problem of ERI for which, unlike the direct problem, the conductivity is now the searched quantity, and by the introduction of a segmentation approach to segment faults on images.
L'usage des drones se démocratise, ouvrant pour les gestionnaires de digues des perspectives ... more L'usage des drones se démocratise, ouvrant pour les gestionnaires de digues des perspectives de reconnaissance et d'auscultation de leurs ouvrages par voie aérienne à des coûts d'opération raisonnables. L'instrumentation de mesure se miniaturise, son coût diminue, et permet une vision globale et profonde des infrastructures, souvent au-delà de ce que peut détecter l'humain, ou avant que les conséquences d'une anomalie majeure ne soient visibles à l'œil nu. DIDRO est un consortium de chercheurs et d'industriels, réunis sous l'impulsion d'opérateurs de drones et de gestionnaires de digues. Trois ans de travaux ont permis de mettre au point des techniques d'acquisition d'image et d'interprétation des résultats pour l'aide à la détection de désordres sur les ouvrages. Cette communication présente le dispositif d'acquisition de données par drones et les outils d'aide à la décision issus d'une acquisition de données par d...
Located at the northwestern edge of the « Pays d’Auge » plateau (Normandy, France), the « Vaches ... more Located at the northwestern edge of the « Pays d’Auge » plateau (Normandy, France), the « Vaches Noires » cliffs are unique on the French coast. With a height around 120m, they are characterized by a badlands morphology. These 4.5 km long cliffs are composed of Jurassic clayey-marly and limestone benchs, topped by a thick chalky series of the Upper Cretaceous. Each evolve under the combined action of subaerial and marine processes.
NSG2021 27th European Meeting of Environmental and Engineering Geophysics, 2021
Summary This study presents the work carried out at the Notre-Dame-du-Val chapel located in Sotte... more Summary This study presents the work carried out at the Notre-Dame-du-Val chapel located in Sotteville-sur-Mer (Normandy, France). Local authorities are considering restoration work and have requested a geophysical survey of the surroundings. First, aerial photography by drone yields a Structure from Motion (SfM) model of the exterior of the chapel, completed by a 3D interior model. Geophysical prospecting consists in imaging shallow surface of surroundings, with help of Ground Penetrating Radar (GPR) and Electrical Resistivity Imaging (ERI). GPR measurements clearly reveal former apses on both sides of the chapel, corresponding to the transepts meets in perfect agreement with the presence of filled-in openings visible in the 3D interior photogrammetric model. The ERI measurements underline the presence of a very resistive substratum, probably corresponding to the local chalky formation where the chapel was built. Besides, resistive formation underlines the potential earthworks carr...
A four-year diachronic study was carried out on coastal badlands cliffs ("les falaises des V... more A four-year diachronic study was carried out on coastal badlands cliffs ("les falaises des Vaches Noires", Normandy, France) to assess erosion and acretion volumes. Cretaceous to Jurassic facies at cliffs face are exposed to erosion activated by rainfalls on the tableland and tempests and high tidals at the bottom. Consequences have a direct impact both (i) on housing and civil engineering structures and (ii) on Le Havre harbor and the Seine river waterways. More than ten aerial drone surveys were carried out between 2016 and 2019. Recorded images by drone led to accurate Digital Elevation Model (DEM) models by means of photogrammetry. Each DEM georeferenced with differential global positionning system (DGPS) were then compared with each other. Near surface geophysical methods were also performed to understand materials and their properties involved in such processes . Cliff edge retreat can be assessed, while eroded and accumulated volumes are locally calculated. With hel...
The thermal convection is numerically computed in 3D fluid satured isotropically fractured porous... more The thermal convection is numerically computed in 3D fluid satured isotropically fractured porous media. Fractures are inserted as 2D convex polygons, which are randomly located. The fluid is assumed to satisfy 2D and 3D Darcy’s law in the fractures and in the porous medium, respectively; exchanges take place between these two structures. First, checks were performed on an unfractured porous medium and the convection cells do start for the theoretical value of Ra, namely 4pi2. 2D convection was verified up to Ra=800. Second, all fractured simulations were made for Rayleigh numbers (Ra) < 150, cubic boxes and closed-top conditions. The influence of parameters such as fracture aperture (or fracture transmissivity) and fracture density on the heat released by the whole system is studied. Then, the effective permeability of each fractured system is calculated. This last calculation enables the comparison between all fractured models and models of homogeneous medium with the same macr...
We study the influence of the topography of a levee on the electric and magnetic signals obtained... more We study the influence of the topography of a levee on the electric and magnetic signals obtained with the Radio-Magnetotelluric method (RMT) and the Slingram method, respectively. For the RMT method, field measurements have been modelled with a finite element commercial software (AC/DC and Radio-Frequency modules of Comsol Multiphysics). A levee situated in Orleans (France) along the Loire river has been considered in order to design a model taking into account the skin depth and the incident wavelength. The effect of the incident electromagnetic field direction has been assessed with two different incident wave directions: BBC 5 from Salford (UK) and France-Inter from Allouis (France). The simulations highlight the tri-dimensional effects of the topography in the apparent resistivity, observed on the crest of the levee, depending on the incident field direction and topography. For the Slingram method, the magnetic field has been simulated using the AC/DC module of Comsol. The rati...
Surveys in Geophysics, 2020
This article presents a review of the use of unmanned aerial vehicles (UAVs) in the context of ge... more This article presents a review of the use of unmanned aerial vehicles (UAVs) in the context of geohazards. The pluri-disciplinary role of UAVs is outlined in numerous studies associated with mass earth movements, volcanology, flooding events and earthquakes. Scientific advances and innovations of several research teams around the world are presented from pre-events investigations to crisis management. More particularly, we emphasize the actual status of technology, methodologies and different applications that have emerged with the use of UAVs for each domain. It is shown that the deployment of UAVs in the geohazards context has experienced a tremendous increase during the last 10 years, with the development of more and more miniaturized, flexible and reliable systems. The use of such technology (UAV platform, instrumentation, methodologies) is different for each domain, depending on the spatial extent and the time scale of the observed phenomenon, but also on the practical constraints associated with the civil aviation agencies regulations (outside or within urban areas, before or during a crisis…). This paper also highlights the use of recent methodologies associated with semi-automatic/automatic segmentation or deep learning for the processing of important amounts of data provided by UAVs. Finally, although still sparse, the joint use of UAVs and satellite data is progressing and remains a challenge for future studies in the context of geohazards.
Bulletin of Engineering Geology and the Environment, 2020
This study aims to realize a regional scale 3D geological model (3D-GM) of the Pays d'Auge Platea... more This study aims to realize a regional scale 3D geological model (3D-GM) of the Pays d'Auge Plateau (PAP), in Normandy, France, leading to the study of the Vaches Noires Cliffs (VNCs), a local coastal site. A 3D-GM is built using a 3D implicit method based on the integration of surface geology, cross sections, and elevation data. The geometry of the geological layers is characterized, leading to an estimation of the volume of each geological unit and of the water resource within the Cretaceous aquifer of the study site. A hydrogeological model of the VNCs is proposed and the role of clayey soils on the erosive process of the cliffs is considered. Lastly, potential applications of 3D-GM are discussed in the framework of further researches on coastal retreat in Normandy.
Journal of Coastal Research, 2019
Archaeological Prospection, 2018
A geophysical survey was carried out in 2015 for the development of the patrimonial site of the A... more A geophysical survey was carried out in 2015 for the development of the patrimonial site of the Abbey of Our Lady of Bec (also called the Bec Abbey), located in Le Bec‐Héllouin, Normandy, France. This survey aimed at optimizing the future accessibility programme by preserving the historical heritage of the Bec Abbey, taking into account potential underground remains. The ground penetrating radar (GPR), the electrical resistivity imaging (ERI) and the magnetic method (MM) were used to prospect the shallow surface. The GPR imaging shows longitudinal and curvated structures, drawing the classical and simplified plan of a Romanesque church basement of the eleventh century. This is the most important discovery of this survey, since the existence of this church was historically known but has remained unlocated till this geophysical survey. The ERI measurements confirm and locally complete most of the GPR results. Despite the very magnetic‐noisy environment, the MM investigation is the onl...
Landslides, 2018
High-resolution digital elevation models (HRDEMs) on coastal areas, particularly cliffs, are an i... more High-resolution digital elevation models (HRDEMs) on coastal areas, particularly cliffs, are an important asset for analyzing and quantifying the processes affecting their morphology. The Vaches-Noires coastal cliffs, located at the northwestern part of the Pays-d'Auge region (Normandy, France), are an ideal site for the study of subaerial and marine erosion processes. Indeed, the coastline evolves through the accumulation of deposits resulting from rotational landslides and/or mudflows at the base of the cliff which are then undermined by the sea. The 3D modeling of a representative sector of the cliffs appears a suitable solution to monitor and quantify this evolution using HRDEMs. This paper presents the whole of a monitoring protocol, with high spatial resolution and high temporal resolution, on an original location characterized by reliefs of Badlands in coastal environments. The first results of these investigations are described with an evaluation of two methods for the creation of 3D models: a Bheavym ethod by Terrestrial Laser Scanning (TLS) monitoring, and a Blight^method using BStructure from Motion^(SfM) terrestrial photogrammetry. The small investment of time in the field and money is an important asset of the SfM method. The textured rendering quality of the SfM model makes it a powerful tool for geomorphological analysis. According to a recurrent monitoring protocol involving both measurements, it was possible to compare the accuracy of the SfM and TLS models. The results show a high accuracy of the SfM models with an overall average error of 0.05 m. The representations of the zones of accumulation and erosion as well as their spatial succession allow to investigate the dynamics of the involved processes with both methods. Preliminary volume calculation results are conclusive for TLS models.
GEOPHYSICS, 2017
The monitoring of underground cavities plays a key role in risk management policies. Mine and und... more The monitoring of underground cavities plays a key role in risk management policies. Mine and underground quarry stakeholders require relevant methodologies and practices to define and assess hazards associated with these structures. To monitor these structures, geophysical methods may offer an interesting compromise among operating cost, invasiveness, and risk assessment reliability. The use of conventional 3D-electric resistivity imaging (ERI) software validated on relatively flat media is not sufficient to efficiently assess complex 3D geometries such as underground mine pillars. We have developed a new approach to evaluate pillar condition by means of a sequential use of two techniques. First, the photogrammetric method yields a detailed 3D model of the pillar geometry from a set of pictures. Second, 3D-ERI is performed based on this suitable geometry. The methodology is tested on a synthetic model to evaluate the effect of various geometry resolutions on the inversion. We also ...
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Papers by Raphael Antoine