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| Jaud, Marion; Letortu, Pauline; Augereau, Emmanuel; Le Dantec, Nicolas; Beauverger, Mickael; Cuq, Veronique; Prunier, Christophe; Le Bivic, Rejanne; Delacourt, Christophe. |
| The georeferencing process is crucial to the accuracy of terrestrial laser scanner (TLS) data, in particular in the context of diachronic studies relying on multi-temporal surveys. The use of Ground Control Points in the georeferencing process can however be complex when confronted with the practical constraints of coastal surveying. A simple and quick alternative method called "pseudo-direct georeferencing" is proposed in the present paper. This method involves internal inclinometers to measure roll and pitch angles and a centimetric GPS to measure the position of the TLS center and the position of one backsight target. When assessing the transformational uncertainty by using a set of independent ground validation points for both classical indirect and... |
| Tipo: Text |
Palavras-chave: Terrestrial laser scanning; Coastal monitoring; Direct georeferencing; Indirect georeferencing; Multi-temporal surveys; Geomorphological evolution. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75050/75683.pdf |
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| Jaud, Marion; Passot, Sophie; Le Bivic, Rejanne; Delacourt, Christophe; Grandjean, Philippe; Le Dantec, Nicolas. |
| For monitoring purposes and in the context of geomorphological research, Unmanned Aerial Vehicles (UAV) appear to be a promising solution to provide multi-temporal Digital Surface Models (DSMs) and orthophotographs. There are a variety of photogrammetric software tools available for UAV-based data. The objective of this study is to investigate the level of accuracy that can be achieved using two of these software tools: Agisoft PhotoScan((R)) Pro and an open-source alternative, IGN((c)) MicMac((R)), in sub-optimal survey conditions (rugged terrain, with a large variety of morphological features covering a range of roughness sizes, poor GPS reception). A set of UAV images has been taken by a hexacopter drone above the Riviere des Remparts, a river on... |
| Tipo: Text |
Palavras-chave: Image processing; SfM photogrammetry software; Digital Surface Model; UAV; Orthophoto; Accuracy assessment. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00639/75081/75581.pdf |
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| Nichols, C. Reid; Wright, Lynn D.; Bainbridge, Scott J.; Cosby, Arthur; Henaff, Alain; Loftis, Jon D.; Cocquempot, Lucie; Katragadda, Sridhar; Mendez, Gina R.; Letortu, Pauline; Le Dantec, Nicolas; Resio, Donald; Zarillo, Gary. |
| Impacts from natural and anthropogenic coastal hazards are substantial and increasing significantly with climate change. Coasts and coastal communities are increasingly at risk. In addition to short-term events, long-term changes, including rising sea levels, increasing storm intensity, and consequent severe compound flooding events are degrading coastal ecosystems and threatening coastal dwellers. Consequently, people living near the coast require environmental intelligence in the form of reliable short-term and long-term predictions in order to anticipate, prepare for, adapt to, resist, and recover from hazards. Risk-informed decision making is crucial, but for the resulting information to be actionable, it must be effectively and promptly communicated... |
| Tipo: Text |
Palavras-chave: Coastal observations; Numerical models; Coastal flooding; Big data; Collaboration; Community vulnerability; Climate change; Urban coasts. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74921/75770.pdf |
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| Jaud, Marion; Delacourt, Christophe; Le Dantec, Nicolas; Allemand, Pascal; Ammann, Jerome; Grandjean, Philippe; Nouaille, Henri; Prunier, Christophe; Cuq, Veronique; Augereau, Emmanuel; Cocquempot, Lucie; Floc'H, France. |
| In the dual context of coastal hazard intensification and the growing number of stakes exposed to these hazards, coastal observatories are in demand to provide a structured framework dedicated to long-term monitoring. This article describes the drone-based photogrammetry monitoring performed since 2006 on Porsmilin Beach (Brittany, France) in the framework of the DYNALIT (Littoral and Coastline Dynamics) observatory, focusing on data quality and the consistency of long-term time series under the influence of multiple technological evolutions: Unmanned Aerial Vehicles (UAV) platforms with the arrival of electric multirotor drones, processing tools with the development of structure-from-motion (SfM) photogrammetry, and operational modes of survey. A study... |
| Tipo: Text |
Palavras-chave: UAV; SfM photogrammetry; Coastal observatory; Beach monitoring. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74927/76116.pdf |
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| Jaud, Marion; Le Dantec, Nicolas; Ammann, Jerome; Grandjean, Philippe; Constantin, Dragos; Akhtman, Yosef; Barbieux, Kevin; Allemand, Pascal; Delacourt, Christophe; Merminod, Bertrand. |
| Hyperspectral imagery has proven its potential in many research applications, especially in the field of environmental sciences. Currently, hyperspectral imaging is generally performed by satellite or aircraft platforms, but mini-UAV (Unmanned Aerial Vehicle) platforms (<20 kg) are now emerging. On such platforms, payload restrictions are critical, so sensors must be selected according to stringent specifications. This article presents the integration of a light pushbroom hyperspectral sensor onboard a multirotor UAV, which we have called Hyper-DRELIO (Hyperspectral DRone for Environmental and LIttoral Observations). This article depicts the system design: the UAV platform, the imaging module, the navigation module, and the interfacing between the... |
| Tipo: Text |
Palavras-chave: Unmanned Aerial Vehicle (UAV); Hyperspectral mapping; Georectification; Hyperspectral cube reconstruction. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00638/74998/75794.pdf |
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| Jaud, Marion; Grasso, Florent; Le Dantec, Nicolas; Verney, Romaric; Delacourt, Christophe; Ammann, Jerome; Deloffre, Julien; Grandjean, Philippe. |
| Intertidal mudflats play a critical role in estuarine exchange, connecting marine and continental supplies of nutrients and sediments. However, their complex morphodynamics, associated with a wide range of physical and biological processes, are still poorly understood and require further field investigation. In addition, mudflats are challenging areas for Structure-from-Motion (SfM) photogrammetric surveys. Indeed, the mudflats generally hold back residual tidal water, which can make stereo restitution particularly difficult because of poor correlations or sun-glint effects. This study aims to show the potential of light UAVs (Unmanned Aerial Vehicles) for monitoring sedimentary hydrodynamics at different spatial scales in a silty estuary. For each UAV... |
| Tipo: Text |
Palavras-chave: Coastal monitoring; Unmanned Aerial Vehicle; Photogrammetry; Estuary; Mudflat areas; Morphological features. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00326/43721/43167.pdf |
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| Mahabot, Marie-myriam; Jaud, Marion; Pennober, Gwenaelle; Le Dantec, Nicolas; Troadec, Roland; Suanez, Serge; Delacourt, Christophe. |
| Under natural and anthropogenic pressure, the coastal regions are evolving rapidly (population growth, erosion, modification of services, etc.), and some of these changes increase their vulnerability. Monitoring the evolution of the coastal regions has thus become essential to understand how they respond to the various pressures and to define how their resilience could be increased. Among other outcomes, such monitoring should provide continuous, high-resolution data on the spatial and temporal evolution of the coastal areas, especially the shoreline zone. One appropriate way to acquire long, continuous, time series of data is to set up a permanent observatory in the zone to be monitored. This paper aims to provide recommendations and a methodological... |
| Tipo: Text |
Palavras-chave: Carbonate beaches; Coral reef; Coastal observatory; UAV; TLS; Bathymetric Lidar. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75013/75695.pdf |
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| Gandois, Henri; Stephan, Pierre; Cuisnier, David; Hulot, Olivia; Ehrhold, Axel; Paul, Marine; Le Dantec, Nicolas; Franzetti, Marcaurelio. |
| This reports on a project that combined evidence gleaned from aerial photographs, place-names, interviews, topography, LIDAR data, and sonar bathymetry to locate stone tidal fish weirs in the Molene Archipelago. The results were verified by diver and pedestrian visual surveys. Models of Holocene sea-level change allowed a group of possibly Late Mesolithic-Early Neolithic weirs to be recognized, with a second group broadly dated to the later Neolithic-Early Bronze Age. The construction of these long megalithic structures is compared to the funerary monuments for which the Molene Archipelago is well known, in terms of technique, cost, and societal organization. |
| Tipo: Text |
Palavras-chave: Tidal weirs fish traps Mol<; Bold>; E<; /bold>; Ne Archipelago megalithic constructions sea-level change Mesolithic Neolithic. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00430/54208/55907.pdf |
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| Meur-ferec, Catherine; Le Berre, Iwan; Cocquempot, Lucie; Guillou, Elisabeth; Henaff, Alain; Lami, Thibaut; Le Dantec, Nicolas; Letortu, Pauline; Philippe, Manuelle; Nous, Camille. |
| Coastal development, combined with the intrinsic mobility of coasts and the context of climate change, tends to increase the vulnerability of coastal territories. This article proposes, on one hand, a renewed interdisciplinary approach to the concept of vulnerability allowing to overcome the nature/society dichotomy. On the other hand, the paper presents an inter-sectoral researchers-managers approach to build a series of indicators to monitor the four components of systemic vulnerability (hazards, stakes, management and representations). These indicators lay the ground for an integrated observatory, source of data for research as well as to inform decisions regarding the adaptation of coastal territories. |
| Tipo: Text |
Palavras-chave: Coastal risks; Erosion; Sea-flooding; Vulnerability; Interdisciplinary; Intersectorality; Indicators; Adaptation; Observatory. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00629/74122/73559.pdf |
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