Efficient Encoding of n-D Combinatorial Pyramids

International audienceCombinatorial maps define a general framework which allows to encode any subdivision of an n-D orientable quasi-manifold with or without boundaries. Combinatorial pyramids are defined as stacks of successively reduced combinatorial maps. Such pyramids provide a rich framework which allows to encode fine properties of objects (either shapes or partitions). Combinatorial pyramids have first been defined in 2D, then extended using n-D generalized combinatorial maps. We motivate and present here an implicit and efficient way to encode pyramids of n-D combinatorial maps

Un algorithme Hongrois pour l'appariement de graphes avec correction d'erreurs

International audienceBipartite graph matching algorithms become more and more popular to solve error-correcting graph matching problems and to approximate the graph edit distance of two graphs. However, the memory requirements and execution times of this method are respectively proportional to (n + m) 2 and (n + m) 3 where n and m are the order of the graphs. Subsequent developments reduced these complexities. However , these improvements are valid only under some constraints on the parameters of the graph edit distance. We propose in this paper a new formulation of the bipartite graph matching algorithm designed to solve efficiently the associated graph edit distance problem. The resulting algorithm requires O(nm) memory space and O(min(n, m) 2 max(n, m)) execution times.L'appariement de graphes biparti deviennent de plus en plus populaires pour résoudre des problèmes d'appariement de graphes avec correction d'erreurs et pour approximer la distance d'édition sur graphes. Cependant, les exigences en mémoire et temps de calcul de cette méthode sont respectivement proportionnels à (n + m)^2 et (n + m)^3 où n et m représentent la taille des deux graphes. Des développements ultérieurs ont réduit ces complexités. Cependant, ces améliorations ne sont valables que sous certaines contraintes sur les paramètres de la distance d'édition. Nous proposons dans cet article une nouvelle formulation de l'algorithme Hongrois conçu pour résoudre efficacement le problème de distance d'édition associé. L'algorithme résultat nécessite un espace mémoire O (nm) et des temps d'exécution O (min (n, m)^2 max (n, m))

GEDLIB: Une bibliothèque C++ pour le calcul de la distance d'édition sur graphes

International audienceThe graph edit distance (GED) is a flexible graph dissimilarity measure widely used within the structural pattern recognition field. In this paper, we present GEDLIB, a C++ library for exactly or approximately computing GED. Many existing algorithms for GED are already implemented in GEDLIB. Moreover, GEDLIB is designed to be easily extensible: for implementing new edit cost functions and GED algorithms, it suffices to implement abstract classes contained in the library. For implementing these extensions, the user has access to a wide range of utilities, such as deep neural networks, support vector machines, mixed integer linear programming solvers, a blackbox optimizer, and solvers for the linear sum assignment problem with and without error-correction

Graph médian généralisé via des minimisations alternées.

International audienceComputing a graph prototype may constitute a core element for clustering or classification tasks. However, its computation is an NP-Hard problem, even for simple classes of graphs. In this paper, we propose an efficient approach based on block coordinate descent to compute a generalized median graph from a set of graphs. This approach relies on a clear definition of the optimization process and handles labeling on both edges and nodes. This iterative process optimizes the edit operations to perform on a graph alternatively on nodes and edges. Several experiments on different datasets show the efficiency of our approach.Calculer un graphe prototype peut constituer une étape centrale pour des méthodes de clustering ou de classification. Toutefois, ce calcul est NP-difficile même pour des classes de graphes simples. Nous proposons dans ce papier une approche efficace basée sur une minimisation alternée pour calculer le graphe médian d'un ensemble. Cette approche s'appuie sur une définition claire du processus d'optimisation et inclue l'étiquetage à la fois des nœuds et des arêtes. Ce processus itératif optimise les opérations à effectuer alternativement sur les sommets et les arêtes. Plusieurs expériences sur des jeux de données différents montrent l'efficacité de notre approche

A Toolkit for Exploring Augmented Reality Through Construction with Children

International audienceAugmented Reality begins to be widely mainstream among children, due to some interactive successes in video games and social networks. Based on this interest, we present CartonEd, an open and complete toolkit suitable for children dedicated to the construction of an augmented reality headset device. The toolkit let the children play and explore augmented reality with and beyond handheld devices. Inspired by the Do-It-Yourself movement, the toolkit includes different components such as blueprints, tutorials, videos, mobile apps, a software development kit and an official website. Among the mobile applications, one is implemented to guide the children through the construction process while experiencing augmented reality. To validate our solution (in particular the construction process and the guiding app) and understand its effect on children in regard to their relation to the augmented reality, we conducted four construction sessions. Our study examines the usability of the guiding app and the construction process. We report in this paper the main components of the CartonEd toolkit and the results of an evaluation among 57 children and teenagers (ages 8-16), showing a positive outcome about their own constructed device (all functional), their feelings and wishes regarding the augmented reality

CARTON Project: Do-It-Yourself Approach to Turn a Smartphone into a Smart Eyewear

International audienceThis paper presents a tool to transform a smartphone into a smart eyewear, named "CARTON", following a Do-It-Yourself (DIY) approach. The hardware prototype is made with very simple materials and regular tools we could find anywhere. It also includes a Software Development Kit (SDK) with samples in order to easily adapt or develop new mobile app compatible with this kind of device. By providing everything open-source and open-hardware, we intend to solve the reachability of technologies related to smart eyewear and aim to accelerate research around it. Users experiments were conducted in which participants were asked to create, by themselves, the CARTON's hardware part and perform usability tests with their own creation. Qualitative user feedback and quantitative results prove that CARTON is functional and feasible by anyone, without specific skills

Upper Bounding the Graph Edit Distance Based on Rings and Machine Learning

The graph edit distance (GED) is a flexible distance measure which is widely used for inexact graph matching. Since its exact computation is NP-hard, heuristics are used in practice. A popular approach is to obtain upper bounds for GED via transformations to the linear sum assignment problem with error-correction (LSAPE). Typically, local structures and distances between them are employed for carrying out this transformation, but recently also machine learning techniques have been used. In this paper, we formally define a unifying framework LSAPE-GED for transformations from GED to LSAPE. We also introduce rings, a new kind of local structures designed for graphs where most information resides in the topology rather than in the node labels. Furthermore, we propose two new ring based heuristics RING and RING-ML, which instantiate LSAPE-GED using the traditional and the machine learning based approach for transforming GED to LSAPE, respectively. Extensive experiments show that using rings for upper bounding GED significantly improves the state of the art on datasets where most information resides in the graphs' topologies. This closes the gap between fast but rather inaccurate LSAPE based heuristics and more accurate but significantly slower GED algorithms based on local search

Contribution à la modélisation explicite des plates-formes d'exécution pour l'IDM

23 pagesNational audienceOne foundation of the model driven engineering (MDE) is to separate the modelling application description from its technological implementation (i.e. platform). Some of them are dedicated to the system execution. Hence, one promise solution of the MDE is to automate transformations from platform independent models to platform specific models. Little work has explicitly described platform characteristics. Yet, an explicit modelling allows taking in account their characteristics more easily (par ex., performances, maintainability,portability). This paper presents both an execution platform modelling state of art and a pattern to describe execution platform modelling framework. It intends to confirm the feasibility and the interests in describing an execution platform metamodel

MODELISATION 3D DE ROUTES PAR TELEMETRIE LASER EMBARQUEE POUR LA MESURE DE DISTANCE DE VISIBILITE

National audienceLa plateforme LARA-3D, développée au Centre de Robotique de Mines Paris, est un système de télémétrie laser embarquée sur véhicule permettant de numériser des environnements routiers ou urbains à la vitesse du déplacement, et d'obtenir ainsi des nuages de points 3D denses. Nous présentons l'utilisation de ce système à des fins de mesure de distances de visibilité sur des routes, effectuée dans le cadre du projet SARI/VIZIR, en partenariat avec le LRPC de Strasbourg