Liste de toutes les manifestations à venir et passées proposées par l'équipe SIS.
Liste des manifestations à venir
Jeudi 2 novembre 2017 14:00 to 16:00
Liste des manifestations passées
Jeudi 14 septembre 2017 14:00 to 16:00
Présentation de Signet
Présentation de Signet
Jeudi 6 juillet 2017 14:00 to 16:00
Présentation de Morpheme
Présentation de Morpheme
Jeudi 15 juin 2017 16:00
Data-driven design of orthogonal wavelets with compact support and vanishing moments
We present a framework to design an orthogonal wavelet with compact support and vanishing moments, tuned to a given application in a data-driven way.
This is achieved by optimizing a criterion, such that a prototype signal, which is characteristic for the application, becomes sparse in the wavelet domain.
This approach is beneficial for compression and detection purposes.
Starting from a filter bank approach with lossless polyphase matrices, a parameterization is developed for which orthogonality and compact support are built in, and in terms of which we can express the vanishing moment conditions conveniently. For low order filters the vanishing moment conditions can be built in as well, for high order filters one should resort to constrained optimization. The approach is developed for critically sampled wavelet transforms as well as for the stationary wavelet transform. A few examples illustrate the wavelets generated by these methods.
Jeudi 4 mai 2017 14:00 to 16:00
Présentation de Mediacoding
Présentation de Mediacoding
Jeudi 23 mars 2017 10:00 to 11:00
Détection de nano-objets dans des images industrielles
L'objectif de ce travail est d'être capable de détecter des nano-particules dans des images industrielles et de définir des indicateurs statistiques, et des procédures d'estimation associées, permettant de quantifier la répartition de ces nano-particules (répartition spatiale, agrégation ou pas....).
Nous avons effectué une phase de preprocessing des données. Les images industrielles dont nous disposons étant issues de mesures par microscopie à force atomique, nous devons corriger des dérives de l'appareil de mesure.
Nous cherchons ensuite à estimer des caractéristiques de nos nanos objets en combinant ces mesure AFM avec une autre technique d’imagerie (MEB). J’expliquerai notre premiers résultats qui sont basés sur des techniques d'agrégation d'estimateurs
Jeudi 2 mars 2017 14:00 to 16:00
Présentation de Design
Présentation de Design
Jeudi 9 février 2017 14:00 to 16:00
Présentation des activités de l'équipe SIGNAL
Jeudi 5 janvier 2017 14:00
Construction d'un projet I3S/Géoazur autour des signaux sismologiques
COMRED, MDSC, SIS, SPARKS
Nous souhaiterions développer un projet entre Géoazur et I3S pour créer un programme qui permettra de détecter, extraire et ranger dans une librairie tous ces signaux. Au cours de ce séminaire, je vous présenterai les différents types de signaux que nous utilisons et ce que nous en faisons, les autres signaux qui sont enregistrés par les stations en mer, pour ensuite développer ce que nous souhaiterions faire grâce à vos compétences.
Vendredi 9 décembre 2016 10:30 to 11:30
Introduction à la classification multi-labels : application aux données médicales
SIS / Morpheme
En classification traditionnelle, chaque échantillon à classer se voit attribuer une classe unique, contexte dit mono-label. La classification multi-labels représente une extension où un échantillon à classer peut être associé à plusieurs classes simultanément.
Dans le domaine médical, l'application de la classification multi-labels s'avère particulièrement adaptée puisque les patients peuvent être atteints de plusieurs pathologies simultanément. Or, l'utilisation d'une méthode mono-label par pathologie ne permet pas de prendre en compte les corrélations potentielles entre pathologies. Nous verrons les deux grandes familles de méthodes multi-labels (les méthodes d'adaptation et par transformation) ainsi qu'une application aux données MAPA (Mesure Ambulatoire de la Pression Artérielle).
Title: Introduction to multi-label classification: application to medical data
In traditional classification, each sample to be classified is assigned a single class, also called mono-label classification. The multi-label classification represents an extension where a sample can be associated with several classes simultaneously.
In the medical field, the application of multi-label classification is particularly adapted since patients may be suffering from several pathologies simultaneously. Indeed, the use of one mono-label method per pathology does not allow to take into account the potential correlations between pathologies. We will see the two main families of multi-label methods (adaptation and transformation methods) as well as an application to ABPM data (Ambulatory Blood Pressure Monitoring).
Vendredi 25 novembre 2016 14:00 to 15:00
Optimization of non-convex functionals
Many problems in signal and image processing can be formulated as the minimization of a cost functional with additional constraints related to prior knowledge. The most simple such functional being ||Ax-d|| (where d is some measurement) possibly subject to a linear constraint on x, which has an exact solution provided by the least squares method. In other applications a sparsity constraint on x is more relevant, leading to a non-convex functional f(x)=||Ax-d||+"the amount of nonzero elements in x". The corresponding l0-l2 minimization problem is hard, non-convex and usually has a multitude of local minima. Another problem in the same category is that of finding a low rank matrix satisfying certain additional restrictions.
In my talk I will present an overview of such problems, provide theory for the convex envelope of the functional f and show how the convex envelope can be used to find approximate solutions to the problem, as well as examples of how the convex envelope can help us understand the performance (and prove convergence) of algorithms designed for convex functionals, applied to non-convex ones.
Lundi 7 novembre 2016 15:00
Reconstruction des surfaces de révolution en temps réel à partir de données SLAM denses
La reconstruction géométrique d'une scène basée sur des données 3D est importante car elle possède de nombreuses applications. Dans un premier temps, il faut détecter l’ensemble des formes primitives (par exemple cylindres, sphères, cônes, etc.) qui composent la scène 3D avant d’ensuite tenter d’établir des relations entre elles. Les formes primitives détectées automatiquement par les méthodes existantes sont souvent assez limitées.
Je présente une méthode tirant profit de la symétrie des surfaces de révolution, afin de reconstruire la géométrie de la surface de révolution de manière précise et efficace. J'illustre la pertinence de la méthode en reconstruisant des surfaces de révolution en temps réel dans un environnement issu d’un SLAM dense.
Lundi 7 novembre 2016 14:00
Recalage robuste à base de motifs de points pseudo aléatoires pour la réalité augmentée
La Réalité Augmentée vise à afficher des informations numériques virtuelles sur des images réelles. Le recalage est important, puisqu’il permet d'aligner correctement les objets virtuels dans le monde réel. Contrairement au tracking qui recale en utilisant les informations de l’image précédente, la localisation à grande échelle (wide baseline localization)
calcule la solution en utilisant uniquement les informations présentes dans l’image courante. Il permet ainsi de trouver des solutions initiales au problème de recalage (initialisation) et, n’est pas sujet aux problèmes de « perte de tracking ». Le problème du recalage en RA est relativement bien étudié dans la littérature, mais les méthodes existantes fonctionnent principalement lorsque la scène augmentée présente des textures. Pourtant, pour le recalage avec les objets peu ou pas texturés, il est possible d’utiliser leurs informations géométriques qui représentent des caractéristiques plus intrinsèques que les textures. Ce séminaire s’attache au problème de recalage basé sur des informations géométriques, et plus précisément sur les points. Je présente LGC, une nouvelle méthode de recalage de points robustes et rapides. Il peut mettre en correspondance des ensembles de motifs de points 2D ou 3D subissant une transformation dont le type est connu. LGC présente un comportement linéaire en fonction du nombre de points, ce qui permet un tracking en teps-réel. Je montrerai un démo d'augmentation de croquis d'ingénieries.
Jeudi 20 octobre 2016 14:00 to 15:00
Point-spread function reconstruction in ground-based astronomy
SIS / Morpheme
Because of atmospheric turbulence, images of objects in outer space acquired via ground-based telescopes are usually blurry. One way to estimate the blurring kernel or point spread function (PSF) is to make use of the aberration of wavefront received at the telescope, i.e., the phase. However only the low-resolution wavefront gradients can be collected by wavefront sensors. In this talk, I will discuss how to use regularization methods to reconstruct high-resolution phase gradients and then use them to recover the phase and the PSF in high accuracy.
Jeudi 15 septembre 2016 14:30
Image guided protontherapy: recent research and technological innovations to fight cancer
SIS / MediaCoding
Abstract : Proton therapy kills cancer cells by delivering proton beams to the tumour. Opposite to conventional radiation therapy, proton beams deposit their maximum energy within a precisely defined range, known as the Bragg peak. This is due to the stopping power of the atoms in the body of the patient. To proceed the treatment, a plan is draw on a 3D image (a CT scan) of the patient. The Gross Tumour Volum is segmented and the Organs At Risk (OAR) are also identified to be protected during the treatment. The plan allows to maximize the dosis on the tumour and minimize the dosis on the OAR. The patient is treated in the room on the basis of the 3D scan taken before the treatment.
Our research has led to the development of an imaging system (a cone beam CT) which is in the treatment room and which allows to adapt the treatment by using different image processing tools, among which deformable coregistration and contours tracking are essential. This allow to implement adaptive protontherapy, including on mobile tumours (e.g. lung tumours) and reduce the range uncertainties.
Biography : Benoit Macq is Professor at Université catholique de Louvain (UCL). His main research topics are image and video compression, image watermarking, immersive communications, visualization and co-registration for medical imaging.
Benoit Macq is Fellow of the IEEE and has been general chair of IEEE ICIP2011.
Benoit Macq has been Vice-President of UCL from 2009 to 2014 and has founded the Louvain Technology Transfer Office.
Benoit Macq is co-founder of 10 start-ups from his research team.
He is Member of the Royal Academy of Science of Belgium.
Vendredi 26 août 2016 10:00
L1-norm principal component analysis and its link with independent component analysis
SIS / Signal
Abstract: Principal component analysis (PCA) based on L1-norm maximization is an emerging technique that has drawn growing interest in the signal processing and machine learning research communities, especially due to its robustness to outliers. In this talk we will explore some links between L1-norm PCA and ICA. Specifically, we will show that L1-norm PCA can perform independent component analysis (ICA) under the whitening assumption. However, when the source probability distributions fulfil certain conditions, the L1-norm criterion needs to be minimized rather than maximized, which can be accomplished by simple modifications on existing optimal algorithms for L1- PCA with global convergence. If the sources have symmetric distributions, we show in addition that L1-PCA is linked to kurtosis optimization. A number of numerical experiments illustrate the theoretical results and analyze the comparative performance of different algorithms for ICA via L1-PCA.
R. Martín-Clemente, V. Zarzoso, "On the Link between L1-PCA and ICA", IEEE Transactions on Pattern Analysis and Machine Intelligence, 38, 2016.
Short bio: Rubén Martín-Clemente received the M.Eng. Degree in telecommunications engineering and the PhD degree with highest distinction in telecommunications engineering from the University of Seville, Spain, in 1996 and 2000 respectively. Currently, he is associate professor at the Department of Signal Processing and Communications of the University of Seville, Spain. He has been a visiting researcher at the University of Regensburg, Germany. Among other areas, his research interests include multivariate data analysis with emphasis on independent component analysis and its application to biomedical problems. He has authored or co-authored numerous publications on these topics. Dr. Martín-Clemente has served as Program Committee Member for several international conferences and was a Program Committee Chair of the 5th International Conference on Independent Component Analysis and Blind Signal Separation in 2004.
Mardi 2 août 2016 11:00
The use of blind source separation techniques to estimate respiratory parameters through multiple accelerometers
SIS / Signal
Several respiratory, cardiovascular and metabolic disorders are diagnosed and monitored by respiratory measurements such as respiratory rate, tidal volume and breathing pattern. The methods to retrieve these parameters usually require some obtrusion of the air breathed by the patients with is uncomfortable and limited to hospital environments. New respiratory measurement techniques are being developed to overcome these limitations, and one emerging approach involves the use of accelerometers to analyze the thoracic cage movement and estimate the respiratory parameters. We discuss these strategies and also introduce a new system for measure multiple accelerometer signal simultaneously and, using blind source separation, estimate these respiratory parameters.
Biography: Ailton L. D. Siqueira Jr. is an Electrical Engineer, and has received the M. Sc. (2007) and Ph. D. (2013) degrees in biomedical engineering from the Federal University of Uberlândia (Brazil). He is a full time professor on Federal Institute of Triângulo Mineiro since 2010, and currently is a Post-Doctoral Researcher with the I3S SIS team. His research interests include electrical engineering, biomedical engineering, computer systems, digital signal processing, electromyography and medical instrumentation.
Mardi 2 août 2016 10:00
Applications of respiratory waveforms
SIS / Signal
Non obstructive acquisition of respiratory waveforms has applications in several research and clinical scenarios. This presentation will introduce two research fields that can benefit of such system: computerized lung sound analysis and autonomic cardiovascular regulation modeling.
Biography: Raimes Moraes received the B.Sc. degree in electrical engineering from the Federal University of Uberlândia (Brazil) in 1988, the M.Sc. degree in electrical engineering from the State University of Campinas (Brazil), in 1991, and the Ph.D. degree in medical physics from the University of Leicester, (U.K.), in 1995. He is Professor of the Electrical Engineering Department, Federal University of Santa Catarina (Brazil). His research interests include medical instrumentation and discrete-time signal processing applied to biomedical signals.
Lundi 23 mai 2016 14:30 to 15:30
Permettre aux utilisateurs de choisir interactivement son point de vue : un challenge en compression.
SIS / MediaCoding
Abstract : Enabling users to interactively navigate through different viewpoints of a static scene is a new interesting functionality in 3D streaming systems. While it opens exciting perspectives toward rich multimedia applications, it requires the design of novel representations and coding techniques to solve the new challenges imposed by the interactive navigation. In particular, the encoder must prepare a priori a compressed media stream that is flexible enough to enable the free selection of multiview navigation paths by different streaming media clients. Interactivity clearly brings new design constraints: the encoder is unaware of the exact decoding process, while the decoder has to reconstruct information from incomplete subsets of data since the server generally cannot transmit images for all possible viewpoints due to resource constrains. In the presentation, we present what methods already exist and we propose some new solutions in the context of multi-view representations. We also present how these intuitions could be extended to the compression of 3D meshes for the context of user free navigation.
Biography : Thomas Maugey received the M.Sc. degree from the École Supérieure d’Electricité, Supélec, Gif-sur-Yvette, France, and from Université Paul Verlaine, Metz, France, in 2007 in fundamental and applied mathematics. He received the Ph.D. degree in image and signal processing from TELECOM ParisTech, Paris, France, in 2010. From 2010 to 2014, he was a Post-Doctoral Researcher with the Signal Processing Laboratory, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland. He is a Research Scientist with INRIA in the team-project SIROCCO, Rennes, France. His research interests include monoview and multiview distributed video coding, 3D video communication, data representation, video compression, network coding, and view synthesis.
Jeudi 7 avril 2016 10:30
High Performance Control of Quadrotor Aerial Robotic Vehicles
Abstract: Quadrotor aerial vehicles are one of the most flexible and adaptable platforms for aerial robotics research. The impact of the quadrotor in the field of robotics research can be seen as similar to that of the Puma robotic arm in the early years of robotic manipulators, and the unicycle wheeled robot, in a similar period in mobile robotics. Existing research aerial robotics has brought the field to a point where the basics of control and estimation are reasonably well established for quadrotor vehicles although contributions to the basic control design are still being made. This talk provides a high level introduction to the key aspects of quadrotor control as practiced by the majority of laboratories around the world.
Robert Mahony is a Professor in the Research School of Engineering at the Australian National University. He received his BSc in 1989 (applied mathematics and geology) and his PhD in 1995 (systems engineering) both from the Australian National University. He worked firstly as a marine seismic geophysicist and an industrial research scientist before completing a postdoctoral fellowship in France at the Universite de Technologie de Compiegene and a Logan Fellowship at Monash University in Australia. He has held his post at ANU since 2001. His research interests are in non-linear systems theory and optimization with applications in robotics, geometric optimisation techniques and computer vision.
Jeudi 24 mars 2016 14:00 to 15:00
Vision nocturne numérique
SIS / Morpheme
Jeudi 5 novembre 2015 15:00 to 16:00
From real data to virtual copies: a few contributions
SIS / MediaCoding
This talk will cover two applications related to digitization of the real world: one concerning cultural heritage and another on example-based texture synthesis.
I) Treatment of 3D models with acquired radiance.
Vision and computer graphics communities have built methods for digitizing, processing and rendering 3D objects. There is an increasing demand coming from cultural communities for these technologies, especially for archiving, remote studying and restoring cultural artefacts like statues, buildings or caves. Besides digitizing geometry, there can be a demand for recovering the photometry with more or less complexity: simple textures (2D), light fields (4D), SV-BRDF (6D), etc. This talk will cover several contributions that can be situated in the pipeline for constructing and treating surface light fields represented by hemispherical radiance functions attached to a surface. First, we will tackle robustness issues in the aspect reconstruction from photographic data resulting from real-world on-site acquisitions [VSLD13]. And secondly we will present a simplification technique for this data, which locally minimizes the loss of both geometric and photometric detail [VSKLD15].
II) Example-based real-time texturing.
Generating textures in real-time is a must in videogames or other real-time animated worlds. But to create textures quickly, they need to be generated at runtime from compact data stored on the GPU. In this talk we will explain why, and overview two contributions that improve over the state of the art in on-the-fly texture synthesis. The first [VSGLD13] is a new tiling algorithm that augments the amount of variety that can be generated with a single repetitive tile. This is achieved by stochastic exchanges of part of its content in a seamless way. Above that, a multi-scale transition mechanism is added to generate visual detail. The second [GSVDG14] will propose a new noise model for procedural texturing, which are textures stored as compact functions. This new function has been built so that it can be tuned to reproduce an input exemplar containing structured elements in a procedural way, which was unseen before.
[VSLD13] Robust Fitting on Poorly Sampled Data for Surface Light Field Rendering and Image Relighting ; Computer Graphics Forum, vol. 32, issue 6.
[VSGLD13] On-the-Fly Multi-Scale Infinite Texturing from Example ; Proceedings of "ACM SIGGRAPH Asia 2013" conference ; Transactions on Graphics, vol. 31, issue 6.
[GSVDG14] Local random-phase noise for procedural texturing ; Proceedings of "ACM SIGGRAPH Asia 2014" conference ; Transactions on Graphics, vol. 32, issue 6.
[VSKLD15] Simplification of Meshes with Digitized Radiance ; Proceedings of the "Computer Graphics International 2015" conference ; The Visual Journal, vol. 21, issue 6-8.
Mercredi 16 septembre 2015 10:00
Inferring Significance from Biomedical Signals using Principal Component Analysis
SIS / Signal
2ème exposé : mercredi 16 septembre, 10h00.
Résumé : This study was motivated by the biomechanical analysis of human movement, which usually consists of extensive reports with several graphs that are difficult to be interpreted by physicians or athletic trainers. Additionally, in many times, signal analysis is reduced to few parameters extracted from specific points of these signals, whose do not reflect or take into account the complexity of the involved physiologic phenomenon. The principal component analysis (PCA) has enabled the quantitative evaluation of signals by reducing large volumes of data to a small set of parameters, which take into account all the variance presented by the original data. Such parameters have been very useful for the quantitative evaluation of abnormalities, particularly allowing the objective comparison of clinical interventions or physical training strategies. More recently, the analysis of the loading factors of the eigenvectors obtained by PCA are representing an objective method to determine in which points of the signal a given subject shows abnormal differences, when compared to a control group. This brief presentation will include some examples of PCA application: (1) The gait analysis of subjects with Parkinson's syndrome for the objective comparison between treatments with drugs (usually levodopa) and deep brain stimulation of the subthalamic nucleus; (2) Assessment of physiotherapy effects in subjects after unilateral fracture of the lower limb; (3) Development of scores for normal gait and their application in functional evaluation of patients after reconstruction of the anterior cruciate ligament; and (4) It is finalized with an applications in ECG analysis.
Lundi 14 septembre 2015 14:00
A Presentation of the Biomedical Engineering Program - Federal University of Rio de Janeiro
SIS / Signal
1er exposé : lundi 14 septembre, 14h00.
Résumé : This talk comprehends an overview of the Biomedical Engineering Program (PEB) at the Universidade Federal do Rio de Janeiro, including few details of our master and doctoral programs. It follows with a short presentation of our research areas: (1) Biomedical Instrumentation; (2) Health Systems Engineering; (3) Ultrasound in Medicine; (4) Pulmonary Engineering; (5) Biomechanics; and (6) Biomedical Signal Processing. For each area, details of some projects are given.
Mercredi 1 juillet 2015 (All day)
8h30-‐9h Accueil café
• Présentation journée
• Projet MediaCoding, Marc Antonini
• « Contributions for image retrieval in the Wavelet Transform domain », Amani Chaker
• Projet Morpheme, Xavier Descombes
• « Modelling and characterizing axon growth from in vivo data », Agustina Razetti
10h45-‐11h05 P’tite pause
• Projet Signal, Olivier Meste
• « Structured tensor decompositions and multidimensional compressed sensing », Henrique Goulard
• Projet Signet, Guillaume Urvoy-‐Keller
• « Next Generation SDN-‐based Virtualized Datacenters », Myriana Rifail
• « Bien vivre au quotidien avec l'équipe administrative », Marie-‐Pierre Combeau
• Projet Design, Joao Rendas
• « Modélisation et prédiction du risque d'accident de décompression en plongée hyperbare », Asya Metelkina
15h20-‐15h40 P’tite pause
Réunion des permanents
17h30 fin de la Journé
Lundi 22 juin 2015 11:00
Edge co-occurrences can account for rapid categorization of natural versus animal images
Making a judgment about the semantic category of a visual scene, such as whether it contains an animal, is typically assumed to involve high-level associative brain areas. Previous explanations require progressively analyzing the scene hierarchically at increasing levels of abstraction, from edge extraction to mid-level object recognition and then object categorization. Here we show that the statistics of edge co-occurrences alone are sufficient to perform a rough yet robust (translation, scale, and rotation invariant) scene categorization. We first extracted the edges from images using a scale-space analysis coupled with a sparse coding algorithm. We then computed the "association field" for different categories (natural, man-made, or containing an animal) by computing the statistics of edge co-occurrences. These differed strongly, with animal images having more curved configurations. We show that this geometry alone is sufficient for categorization, and that the pattern of errors made by humans is consistent with this procedure. Because these statistics could be measured as early as the primary visual cortex, the results challenge widely held assumptions about the flow of computations in the visual system. The results also suggest new algorithms for image classification and signal processing that exploit correlations between low-level structure and the underlying semantic category.
Mardi 26 mai 2015 (All day) to Mardi 28 juillet 2015 (All day)
SIS / MediaCoding
L’objectif du colloque est de mettre en avant des travaux en cours sur les éléments qui composent la chaîne de numérisation d’objets 3D, mais également de faire émerger de futurs axes de recherche dans les domaines de l’acquisition, de la modélisation, de l'analyse, et du traitement de la géométrie 3D pour le stockage, la manipulation, la visualisation etc.
Mardi 7 avril 2015 14:00
Distributed large-scale tensor decomposition in collaborative networks
Canonical Polyadic Decomposition (CPD), also known as PARAFAC, is a useful tool for tensor factorization. It has found application in several domains including signal processing and data mining. With the deluge of data faced in our societies, large-scale matrix and tensor factorizations become a crucial issue. Few works have been devoted to large-scale tensor factorizations. In this paper, we introduce a fully distributed method to compute the CPD of a large-scale data tensor across a network of machines with limited computation resources. The proposed approach is based on collaboration between the machines in the network across the three modes of the data tensor. Such a multi-modal collaboration allows an essentially unique reconstruction of the factor matrices in an efﬁcient way. We provide an analysis of the computation and communication cost of the proposed scheme and address the problem of minimizing communication costs while maximizing the use of available computation resources.