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A review of image-based tools for automatic fish ageing from otolith features ArchiMer
Carbini, Sebastien; Chessel, Anatole; Benzinou, Abdesslam; Fablet, Ronan; Mahe, Kelig; De Pontual, Helene.
Most of European fish stocks are assessed using age-based models, and otolith interpretation for age estimations costs several million euros annually. In this context, automated ageing systems would provide a mean to 1) standardize ageing, 2) control ageing consistency within and between ageing laboratories 3) build interpreted image data bases ensuring the information conservation and sharing and 4) improve growth studies while reducing the cost of the acquisition of age data. This paper presents a review of different image-based tools for automatic fish ageing from otolith features within the framework of AFISA (EU STREP project on Automated FISh Ageing coordinated by Ifremer). The full automatic ageing process can be divided into three main steps: 1)...
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Ano: 2008 URL: http://archimer.ifremer.fr/doc/00024/13519/10546.pdf
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Automatic morphological detection of otolith nucleus ArchiMer
Cao, Frédéric; Fablet, Ronan.
This paper deals with the automation of the acquisition of age and growth data from the analysis of otolith images. One of the key component of such it system is the automatic detection of the growth center, which serves as the basis for further processing (2D ring segmentation, age and growth estimation,...). To this end, we develop a new and well-founded approach combining a morphological analysis of image level sets to the a contrario, detection principle. This approach leads to a robust parameterless scheme, whose efficiency is demonstrated by an evaluation carried out for a set of several hundred of plaice otoliths. (c) 2005 Elsevier B.V. All rights reserved.
Tipo: Text Palavras-chave: Otolith imaging; A contrario detection; Mathematical morphology.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1223.pdf
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Weakly Supervised Learning: Application to Fish School Recognition ArchiMer
Lefort, Riwal; Fablet, Ronan; Boucher, Jean-marc.
This chapter deals with object recognition in images involving a weakly supervised classification model. In weakly supervised learning, the label information of the training dataset is provided as a prior knowledge for each class. This prior knowledge is coming from a global proportion annotation of images. In this chapter, we compare three opposed classification models in a weakly supervised classification issue: a generative model, a discriminative model and a model based on random forests. Models are first introduced and discussed, and an application to fishenes acoustics is presented. Experiments show that random forests outperform discriminative and generative models in supervised learning but random forests are not robust to high complexity class...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00077/18782/16489.pdf
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Overview of recent progress in fisheries acoustics made by Ifremer with examples from the Bay of Biscay ArchiMer
Trenkel, Verena; Berger, Laurent; Bourguignon, Sebastien; Doray, Mathieu; Fablet, Ronan; Masse, Jacques; Mazauric, Valerie; Poncelet, Cyrille; Quemener, Gael; Scalabrin, Carla; Villalobos, Hector.
This paper provides an overview of the progress Ifremer has made recently in fisheries acoustics and the study of small pelagic fish by: i) pushing observation frontiers using a range of platforms including an autonomous underwater vehicle, AUV, ii) developing measuring instruments and methods and iii) studying fish distributions. Presently, information from several frequencies of single-beam echosounders is routinely collected together with data from the ME70 multibeam echosounder. For onboard data acquisition control the HERMES software was developed. The new MOVIES 3D software includes modules for simultaneous realistic 3D visualisation and post-processing such as bottom detection, school extraction and calculation of descriptors and integration of all...
Tipo: Text Palavras-chave: Multibeam echosounder; Oceanographic AUV; Pelagic fish; Fisheries acoustics.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00000/11165/7517.pdf
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Coupling spectral analysis and hidden Markov models for the segmentation of behavioural patterns ArchiMer
Heerah, Karine; Woillez, Mathieu; Fablet, Ronan; Garren, Francois; Martin, Stephane; De Pontual, Helene.
Background Movement pattern variations are reflective of behavioural switches, likely associated with different life history traits in response to the animals’ abiotic and biotic environment. Detecting these can provide rich information on the underlying processes driving animal movement patterns. However, extracting these signals from movement time series, requires tools that objectively extract, describe and quantify these behaviours. The inference of behavioural modes from movement patterns has been mainly addressed through hidden Markov models. Until now, the metrics implemented in these models did not allow to characterize cyclic patterns directly from the raw time series. To address these challenges, we developed an approach to i) extract new metrics...
Tipo: Text Palavras-chave: Fourier transform; Non negative matrix factorization; Classification; Animal behaviour; European sea bass; Movement ecology; Diurnal and tidal cycles; Biologging; Data storage tags.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00402/51400/51974.pdf
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Brève introduction à la fouille de grandes bases de données océaniques ArchiMer
Maze, Guillaume; Mercier, Herle; Fablet, Ronan; Lenca, Philippe; Piolle, Jean-francois.
Les bases de données marines, alimentées par les satellites et les robots autonomes sous-marins comme les flotteurs du réseau Argo, sont de plus en plus grandes (plusieurs dizaines de gigaoctets et teraoctets) et rapidement évolutives (elles changent d’heure en heure). Cette augmentation spectaculaire de la dimension et de la complexité des données rend difficile leur exploitation avec les outils standards. Or, c’est à partir de l’analyse des données que les chercheurs pourront réaliser de nouvelles découvertes scientifiques sur la dynamique des océans, à grande et petite échelles, et les changements climatiques régionaux et globaux. L'école d’été OBIDAM14 visait à contribuer à lever ces verrous d’analyse en introduisant les méthodes de fouille de données...
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Ano: 2014 URL: http://archimer.ifremer.fr/doc/00216/32710/31075.pdf
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Motion recognition using nonparametric image motion models estimated from temporal and multiscale co-occurrence statistics ArchiMer
Fablet, Ronan; Bouthemy, P.
A new approach for motion characterization in image sequences is presented. It relies on the probabilistic modeling of temporal and scale co-occurrence distributions of local motion-related measurements directly computed over image sequences. Temporal multiscale Gibbs models allow us to handle both spatial and temporal aspects of image motion content within a unified statistical framework. Since this modeling mainly involves the scalar product between co-occurrence values and Gibbs potentials, we can formulate and address several fundamental issues: model estimation according to the ML criterion (hence, model training and learning) and motion classification. We have conducted motion recognition experiments over a large set of real image sequences...
Tipo: Text Palavras-chave: Nonparametric motion analysis; Motion recognition; Multiscale analysis; Gibbs models; Co occurrences; ML criterion.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/00000/10714/9323.pdf
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New insights into behavioural ecology of European seabass off the West Coast of France: implications at local and population scales ArchiMer
De Pontual, Helene; Lalire, Maxime; Fablet, Ronan; Laspougeas, Claire; Garren, Francois; Martin, Stephane; Drogou, Mickael; Woillez, Mathieu.
From 2010 to 2012, 246 data storage tags were deployed on European seabass in the Iroise Natural Marine Park, a marine protected area (MPA) off west Brittany, France. A return rate of 14.6% associated with long time series of data provided new information on fish ecology (e.g. maximum experienced depth greater than 225 m, temperature range 6.80–21.87°C). Depth and temperature series were used to infer individual migration using an innovative hidden Markov model (HMM) especially developed for seabass geolocation. Reconstructed fish tracks revealed that seabass is a partially migratory species, as individuals exhibited either long-distance migrations towards the Bay of Biscay or the Celtic Sea, or residency behaviour in the Iroise Sea. Fidelity to summer...
Tipo: Text Palavras-chave: Cod; Connectivity; Data Storage Tag (DST); Depth; European sea bass; Dicentrarchus labrax; Geolocation; Partial migration; Spawning site fidelity; Temperature; Vertical movement.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00451/56230/57790.pdf
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Spatio-Temporal Interpolation of Cloudy SST Fields Using Conditional Analog Data Assimilation ArchiMer
Fablet, Ronan; Huynh Viet, Phi; Lguensat, Redouane; Horrein, Pierre-henri; Chapron, Bertrand.
The ever increasing geophysical data streams pouring from earth observation satellite missions and numerical simulations along with the development of dedicated big data infrastructure advocate for truly exploiting the potential of these datasets, through novel data-driven strategies, to deliver enhanced satellite-derived gapfilled geophysical products from partial satellite observations. We here demonstrate the relevance of the analog data assimilation (AnDA) for an application to the reconstruction of cloud-free level-4 gridded Sea Surface Temperature (SST). We propose novel AnDA models which exploit auxiliary variables such as sea surface currents and significantly reduce the computational complexity of AnDA. Numerical experiments benchmark the proposed...
Tipo: Text Palavras-chave: Ocean remote sensing data; Data assimilation; Optimal interpolation; Analog models; Multi-scale decomposition; Patch-based representation.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00426/53806/54741.pdf
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Computer vision and otolith: toward a modelisation of the morphogenesis ofaccretionary processes ArchiMer
Chessel, Anatole; Fablet, Ronan; Cao, Frederic.

Otolith are small stone growing according to an accretionary process located in fishes inner ears from which a lot can be learnt about their biology and ecology. Computer vision is one of the mean of systematic analysis of those stone. This paper describe an approach using partial differential equation and variational methods to reconstruct the morphogenesis of an otolith from an image.

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Ano: 2008 URL: https://archimer.ifremer.fr/doc/00479/59096/61734.pdf
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Preparation techniques alter the mineral and organic fractions of fish otoliths: insights using Raman micro-spectrometry ArchiMer
Jolivet, Aurelie; Fablet, Ronan; Bardeau, Jean-francois; De Pontual, Helene.
The high spatial resolution analysis of the mineral and organic composition of otoliths using Raman micro-spectrometry involves rigorous protocols for sample preparation previously established for microchemistry and trace elements analyses. These protocols often include otolith embedding in chemically neutral resin (i.e., resins which do not contain, in detectable concentration, elements usually sought in the otoliths). Such embedding may however induce organic contamination. In this paper, Raman micro-spectrometry reveals the presence of organic contamination onto the surface obtained from the use of epoxy resin, specifically Araldite. This contamination level varies depending on otolith structures. Core and checks, known as structural discontinuities,...
Tipo: Text Palavras-chave: Epoxy resin; Otolith composition; Microstructure; Raman spectrometry.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00138/24965/26372.pdf
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Generalized Pareto for Pattern-Oriented Random Walk Modelling of Organisms' Movements ArchiMer
Bertrand, Sophie; Joo, Rocio; Fablet, Ronan.
How organisms move and disperse is crucial to understand how population dynamics relates to the spatial heterogeneity of the environment. Random walk (RW) models are typical tools to describe movement patterns. Whether Levy or alternative RW better describes forager movements is keenly debated. We get around this issue using the Generalized Pareto Distribution (GPD). GPD includes as specific cases Normal, exponential and power law distributions, which underlie Brownian, Poisson-like and Levy walks respectively. Whereas previous studies typically confronted a limited set of candidate models, GPD lets the most likely RW model emerge from the data. We illustrate the wide applicability of the method using GPS-tracked seabird foraging movements and fishing...
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Ano: 2015 URL: https://archimer.ifremer.fr/doc/00275/38641/37160.pdf
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Altimetry for the future: Building on 25 years of progress ArchiMer
Abdalla, Saleh; Abdeh Kolahchi, Abdolnabi; Adusumilli, Susheel; Aich Bhowmick, Suchandra; Alou-font, Eva; Amarouche, Laiba; Andersen, Ole Baltazar; Antich, Helena; Aouf, Lotfi; Arbic, Brian; Armitage, Thomas; Arnault, Sabine; Artana, Camila; Aulicino, Giuseppe; Ayoub, Nadia; Badulin, Sergei; Baker, Steven; Banks, Chris; Bao, Lifeng; Barbetta, Silvia; Barceló-llull, Bàrbara; Barlier, François; Basu, Sujit; Bauer-gottwein, Peter; Becker, Matthias; Beckley, Brian; Bellefond, Nicole; Belonenko, Tatyana; Benkiran, Mounir; Benkouider, Touati; Bennartz, Ralf; Benveniste, Jérôme; Bercher, Nicolas; Berge-nguyen, Muriel; Bettencourt, Joao; Blarel, Fabien; Blazquez, Alejandro; Blumstein, Denis; Bonnefond, Pascal; Borde, Franck; Bouffard, Jérôme; Boy, François; Boy, Jean-paul; Brachet, Cédric; Brasseur, Pierre; Braun, Alexander; Brocca, Luca; Brockley, David; Brodeau, Laurent; Brown, Shannon; Bruinsma, Sean; Bulczak, Anna; Buzzard, Sammie; Cahill, Madeleine; Calmant, Stéphane; Calzas, Michel; Camici, Stefania; Cancet, Mathilde; Capdeville, Hugues; Carabajal, Claudia Cristina; Carrere, Loren; Cazenave, Anny; Chassignet, Eric P.; Chauhan, Prakash; Cherchali, Selma; Chereskin, Teresa; Cheymol, Cecile; Ciani, Daniele; Cipollini, Paolo; Cirillo, Francesca; Cosme, Emmanuel; Coss, Steve; Cotroneo, Yuri; Cotton, David; Couhert, Alexandre; Coutin-faye, Sophie; Crétaux, Jean-françois; Cyr, Frederic; D’ovidio, Francesco; Darrozes, José; David, Cedric; Dayoub, Nadim; De Staerke, Danielle; Deng, Xiaoli; Desai, Shailen; Desjonqueres, Jean-damien; Dettmering, Denise; Di Bella, Alessandro; Díaz-barroso, Lara; Dibarboure, Gerald; Dieng, Habib Boubacar; Dinardo, Salvatore; Dobslaw, Henryk; Dodet, Guillaume; Doglioli, Andrea; Domeneghetti, Alessio; Donahue, David; Dong, Shenfu; Donlon, Craig; Dorandeu, Joël; Drezen, Christine; Drinkwater, Mark; Du Penhoat, Yves; Dushaw, Brian; Egido, Alejandro; Erofeeva, Svetlana; Escudier, Philippe; Esselborn, Saskia; Exertier, Pierre; Fablet, Ronan; Falco, Cédric; Farrell, Sinead Louise; Faugere, Yannice; Femenias, Pierre; Fenoglio, Luciana; Fernandes, Joana; Fernández, Juan Gabriel; Ferrage, Pascale; Ferrari, Ramiro; Fichen, Lionel; Filippucci, Paolo; Flampouris, Stylianos; Fleury, Sara; Fornari, Marco; Forsberg, Rene; Frappart, Frédéric; Frery, Marie-laure; Garcia, Pablo; Garcia-mondejar, Albert; Gaudelli, Julia; Gaultier, Lucile; Getirana, Augusto; Gibert, Ferran; Gil, Artur; Gilbert, Lin; Gille, Sarah; Giulicchi, Luisella; Gómez-enri, Jesús; Gómez-navarro, Laura; Gommenginger, Christine; Gourdeau, Lionel; Griffin, David; Groh, Andreas; Guerin, Alexandre; Guerrero, Raul; Guinle, Thierry; Gupta, Praveen; Gutknecht, Benjamin D.; Hamon, Mathieu; Han, Guoqi; Hauser, Danièle; Helm, Veit; Hendricks, Stefan; Hernandez, Fabrice; Hogg, Anna; Horwath, Martin; Idžanović, Martina; Janssen, Peter; Jeansou, Eric; Jia, Yongjun; Jia, Yuanyuan; Jiang, Liguang; Johannessen, Johnny A.; Kamachi, Masafumi; Karimova, Svetlana; Kelly, Kathryn; Kim, Sung Yong; King, Robert; Kittel, Cecile M.m.; Klein, Patrice; Klos, Anna; Knudsen, Per; Koenig, Rolf; Kostianoy, Andrey; Kouraev, Alexei; Kumar, Raj; Labroue, Sylvie; Lago, Loreley Selene; Lambin, Juliette; Lasson, Léa; Laurain, Olivier; Laxenaire, Rémi; Lázaro, Clara; Le Gac, Sophie; Le Sommer, Julien; Le Traon, Pierre-yves; Lebedev, Sergey; Léger, Fabien; Legresy, Benoı̂t; Lemoine, Frank; Lenain, Luc; Leuliette, Eric; Levy, Marina; Lillibridge, John; Liu, Jianqiang; Llovel, William; Lyard, Florent; Macintosh, Claire; Makhoul Varona, Eduard; Manfredi, Cécile; Marin, Frédéric; Mason, Evan; Massari, Christian; Mavrocordatos, Constantin; Maximenko, Nikolai; Mcmillan, Malcolm; Medina, Thierry; Melet, Angelique; Meloni, Marco; Mertikas, Stelios; Metref, Sammy; Meyssignac, Benoit; Michaël, Ablain; Minster, Jean-françois; Moreau, Thomas; Moreira, Daniel; Morel, Yves; Morrow, Rosemary; Moyard, John; Mulet, Sandrine; Naeije, Marc; Nerem, Robert Steven; Ngodock, Hans; Nielsen, Karina; Nilsen, Jan Even Øie; Niño, Fernando; Nogueira Loddo, Carolina; Noûs, Camille; Obligis, Estelle; Otosaka, Inès; Otten, Michiel; Oztunali Ozbahceci, Berguzar; P. Raj, Roshin; Paiva, Rodrigo; Paniagua, Guillermina; Paolo, Fernando; Paris, Adrien; Pascual, Ananda; Passaro, Marcello; Paul, Stephan; Pavelsky, Tamlin; Pearson, Christopher; Penduff, Thierry; Peng, Fukai; Perosanz, Felix; Picot, Nicolas; Piras, Fanny; Poggiali, Valerio; Poirier, Étienne; Ponce De León, Sonia; Prants, Sergey; Prigent, Catherine; Provost, Christine; Pujol, M-isabelle; Qiu, Bo; Quilfen, Yves; Rami, Ali; Raney, R. Keith; Raynal, Matthias; Remy, Elisabeth; Rémy, Frédérique; Restano, Marco; Richardson, Annie; Richardson, Donald; Ricker, Robert; Ricko, Martina; Rinne, Eero; Rose, Stine Kildegaard; Rosmorduc, Vinca; Rudenko, Sergei; Ruiz, Simón; Ryan, Barbara J.; Salaün, Corinne; Sanchez-roman, Antonio; Sandberg Sørensen, Louise; Sandwell, David; Saraceno, Martin; Scagliola, Michele; Schaeffer, Philippe; Scharffenberg, Martin G.; Scharroo, Remko; Schiller, Andreas; Schneider, Raphael; Schwatke, Christian; Scozzari, Andrea; Ser-giacomi, Enrico; Seyler, Frederique; Shah, Rashmi; Sharma, Rashmi; Shaw, Andrew; Shepherd, Andrew; Shriver, Jay; Shum, C.k.; Simons, Wim; Simonsen, Sebatian B.; Slater, Thomas; Smith, Walter; Soares, Saulo; Sokolovskiy, Mikhail; Soudarin, Laurent; Spatar, Ciprian; Speich, Sabrina; Srinivasan, Margaret; Srokosz, Meric; Stanev, Emil; Staneva, Joanna; Steunou, Nathalie; Stroeve, Julienne; Su, Bob; Sulistioadi, Yohanes Budi; Swain, Debadatta; Sylvestre-baron, Annick; Taburet, Nicolas; Tailleux, Rémi; Takayama, Katsumi; Tapley, Byron; Tarpanelli, Angelica; Tavernier, Gilles; Testut, Laurent; Thakur, Praveen K.; Thibaut, Pierre; Thompson, Luanne; Tintoré, Joaquín; Tison, Céline; Tourain, Cédric; Tournadre, Jean; Townsend, Bill; Tran, Ngan; Trilles, Sébastien; Tsamados, Michel; Tseng, Kuo-hsin; Ubelmann, Clément; Uebbing, Bernd; Vergara, Oscar; Verron, Jacques; Vieira, Telmo; Vignudelli, Stefano; Vinogradova Shiffer, Nadya; Visser, Pieter; Vivier, Frederic; Volkov, Denis; Von Schuckmann, Karina; Vuglinskii, Valerii; Vuilleumier, Pierrik; Walter, Blake; Wang, Jida; Wang, Chao; Watson, Christopher; Wilkin, John; Willis, Josh; Wilson, Hilary; Woodworth, Philip; Yang, Kehan; Yao, Fangfang; Zaharia, Raymond; Zakharova, Elena; Zaron, Edward D.; Zhang, Yongsheng; Zhao, Zhongxiang; Zinchenko, Vadim; Zlotnicki, Victor.
In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and...
Tipo: Text Palavras-chave: Satellite altimetry; Oceanography; Sea level; Coastal oceanography; Cryospheric sciences; Hydrology.
Ano: 2021 URL: https://archimer.ifremer.fr/doc/00688/79999/82978.pdf
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Shedding Light on Fish Otolith Biomineralization Using a Bioenergetic Approach ArchiMer
Fablet, Ronan; Pecquerie, Laure; De Pontual, Helene; Hoie, Hans; Millner, Richard; Mosegaard, Henrik; Kooijman, Sebastiaan A. L. M..
Otoliths are biocalcified bodies connected to the sensory system in the inner ears of fish. Their layered, biorhythm-following formation provides individual records of the age, the individual history and the natural environment of extinct and living fish species. Such data are critical for ecosystem and fisheries monitoring. They however often lack validation and the poor understanding of biomineralization mechanisms has led to striking examples of misinterpretations and subsequent erroneous conclusions in fish ecology and fisheries management. Here we develop and validate a numerical model of otolith biomineralization. Based on a general bioenergetic theory, it disentangles the complex interplay between metabolic and temperature effects on...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00056/16695/14163.pdf
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Weakly Supervised Classification of Objects in Images Using Soft Random Forests ArchiMer
Lefort, Riwal; Fablet, Ronan; Boucher, Jean-marc.
The development of robust classification model is among the important issues in computer vision. This paper deals with weakly supervised learning that generalizes the supervised and semi-supervised learning. In weakly supervised learning training data are given as the priors of each class for each sample. We first propose a weakly supervised strategy for learning soft decision trees. Besides, the introduction of elms priors for training samples instead of hard class labels makes natural the formulation of an iterative learning procedure. We report experiments for UCI object recognition datasets. These experiments show that recognition performance close to the supervised learning can be expected using the propose framework. Besides, an application to...
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Ano: 2010 URL: http://archimer.ifremer.fr/doc/00030/14119/11371.pdf
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Intercomparison of data-driven and learning-based interpolations of along-track Nadir and wide-swath Swot altimetry observations ArchiMer
Beauchamp, Maxime; Fablet, Ronan; Ubelmann, Clément; Ballarotta, Maxime; Chapron, Bertrand.
Over the last years, a very active field of research aims at exploring new data-driven and  learning-based methodologies to propose computationally efficient strategies able to benefit from  the large amount of observational remote sensing and numerical simulations for the reconstruction,  interpolation and prediction of high-resolution derived products of geophysical fields. In this paper,  we investigate how they might help to solve for the oversmoothing of the state-of-the-art optimal  interpolation (OI) techniques in the reconstruction of sea surface height (SSH) spatio-temporal  fields. We focus on two small 10° x 10° GULFSTREAM and 8° x 10° OSMOSIS regions, part  of the North-Atlantic basin: the GULFSTREAM area is mainly driven by energetic...
Tipo: Text Palavras-chave: Data-driven and learning-based approaches; Interpolation; Benchmarking; Nadir and SWOT altimetric satellite data; Sea surface height (SSH).
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00648/76052/76996.pdf
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Interpolating orientation fields: An axiomatic approach ArchiMer
Chessel, Anatole; Cao, F; Fablet, Ronan.
We develop an axiomatic approach of vector field interpolation, which is useful as a feature extraction preprocessing step. Two operators will be singled out: the curvature operator, appearing in the total variation minimisation for image restoration and inpainting/disocclusion, and the Absolutely Minimizing Lipschitz Extension (AMLE), already known as a robust and coherent scalar image interpolation technique if we relax slightly the axioms. Numerical results, using a multiresolution scheme, show that they produce fields in accordance with the human perception of edges.
Tipo: Text
Ano: 2006 URL: http://archimer.ifremer.fr/doc/00065/17647/15182.pdf
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Spatial Statistics of Objects in 3-D Sonar Images: Application to Fisheries Acoustics ArchiMer
Lefort, Riwal; Fablet, Ronan; Berger, Laurent; Boucher, Jm.
In this letter, we address the characterization of objects in 3-D sonar images of the water column obtained by a multibeam echo sounder. Compared with classic 2-D images from a monobeam echo sounder, these 3-D images provide finer scale observation of the pelagic biomasses and new tools to characterize 3-D distributions. By viewing object patterns as realizations of spatial point processes, we investigate descriptive spatial statistics. This method is then applied to 3-D fisheries acoustics data set for characterization of the distribution of pelagic fish schools. Reported experiments illustrate the relevance of the proposed descriptors. The comparison of our method with 2-D sonar data analysis further demonstrates the information gain from using 3-D sonar...
Tipo: Text Palavras-chave: Fisheries acoustics; Multibeam sensor; Object patterns in images; Point processes; Spatial statistics.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00056/16769/14270.pdf
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Methodological developments for improved bottom detection with the ME70 multibeam echosounder ArchiMer
Bourguignon, Sebastien; Berger, Laurent; Scalabrin, Carla; Fablet, Ronan; Mazauric, Valerie.
Multibeam echosounders and sonars are increasingly used in fisheries acoustics for abundance estimation. Because of reduced side-lobe levels in the beam-array pattern, the new Simrad ME70 multibeam echosounder installed on board Ifremer's RV "Thalassa" has been designed to allow improved detection of fish close to the seabed. To achieve this objective, precise and unambiguous detection of the water-bottom interface is required, which raises the issue of bottom detection, especially in the outer beams. The bottom-detection method implemented in the ME70 is based on the amplitude of the reverberated echo. Such an approach is efficient for vertical beams, but less accurate for beams with higher incidence angles, typically 30°–40° for the beam configurations...
Tipo: Text Palavras-chave: Multibeam echosounder; Fisheries; Bottom detection; Acoustics.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6629.pdf
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Coherent heat patterns revealed by unsupervised classification of Argo temperature profiles in the North Atlantic Ocean ArchiMer
Maze, Guillaume; Mercier, Herle; Fablet, Ronan; Tandeo, Pierre; Radcenco, Manuel Lopez; Lenca, Philippe; Feucher, Charlene; Le Goff, Clement.
A quantitative understanding of the integrated ocean heat content depends on our ability to determine how heat is distributed in the ocean and what are the associated coherent patterns. This study demonstrates how this can be achieved using unsupervised classification of Argo temperature profiles. The classification method used is a Gaussian Mixture Model (GMM) that decomposes the Probability Density Function of a dataset into a weighted sum of Gaussian modes. It is determined that the North Atlantic Argo dataset of temperature profiles con- tains 8 groups of vertically coherent heat patterns, or classes. Each of the temperature profile classes reveals unique and physically coherent heat distributions along the vertical axis. A key result of this study is...
Tipo: Text Palavras-chave: Heat content; Classification North Atlantic; Stratification; Water mass; Thermocline; Argo; Pattern.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00363/47431/47456.pdf
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