Clustering for Different Scales of Measurement - the Gap-Ratio Weighted K-means Algorithm

This paper describes a method for clustering data that are spread out over large regions and which dimensions are on different scales of measurement. Such an algorithm was developed to implement a robotics application consisting in sorting and storing objects in an unsupervised way. The toy dataset used to validate such application consists of Lego bricks of different shapes and colors. The uncontrolled lighting conditions together with the use of RGB color features, respectively involve data with a large spread and different levels of measurement between data dimensions. To overcome the combination of these two characteristics in the data, we have developed a new weighted K-means algorithm, called gap-ratio K-means, which consists in weighting each dimension of the feature space before running the K-means algorithm. The weight associated with a feature is proportional to the ratio of the biggest gap between two consecutive data points, and the average of all the other gaps. This method is compared with two other variants of K-means on the Lego bricks clustering problem as well as two other common classification datasets.Comment: 13 pages, 6 figures, 2 tables. This paper is under the review process for AIAP 201

Generating Random Permutations in the Framework of Parallel Coarse Grained Models

We present three algorithms for generating random permutations in the coarse grained model CGM. For each of the proposed algorithms, we study the number of supersteps, the size of the local memory, the overall communicat- ion cost and we check if it gives a permutation with the uniform distribution or not. The proposed algorithms are intended to be simple and of practical relevance. The difficulty, in this paper, lies in proving that they are the desired properties

Procedural Cloudscapes

International audienceWe present a phenomenological approach for modeling and animating cloudscapes. We propose a compact procedural model for representing the different types of cloud over a range of altitudes. We define primitive-based field functions that allow the user to control and author the cloud cover over large distances easily. Our approach allows us to animate cloudscapes by morphing: instead of simulating the evolution of clouds using a physically-based simulation, we compute the movement of clouds using key-frame interpolation and tackle the morphing problem as an Optimal Transport problem. The trajectories of the cloud cover primitives are generated by solving an Anisotropic Shortest Path problem with a cost function that takes into account the elevation of the terrain and the parameters of the wind field

L'animal et l'élevage dans les espaces agraires, l'alimentation des villes et les politiques agricoles : spécificités et complémentarité avec les autres activités rurales. Synthèse des communications du thème 3

International audienceCe thème a suscité 16 communications portant sur le secteur de l'élevage, les systèmes d'élevage, l'agro-pastoralisme et la santé animale. Elles décrivent la diversité, les dynamiques en cours et les priorités d'intervention. Dans les savanes, les enjeux de l'élevage portent sur: i) la redéfinition des politiques d'élevage, l'organisation du commerce et la réorganisation des services de santé, ii) la sécurisation de l'accès aux ressources pastorales et de la mobilité du cheptel, ce qui requiert une organisation des éleveurs, iii) l'émergence de systèmes techniques adaptés aux contexte, avec un renforcement des synergies agriculture-élevage et dans certains cas une intensification raisonnée, iv) le soutien à l'émergence d'élevages périurbains grâce à une évolution des modalités de transfert aux producteurs par la voie du conseil. Désormais, la recherche en relation avec le développement, se doivent de fournir aux éleveurs, et aux agro-éleveurs des références et des outils d'aide à la décision collectives et individuelles adaptées à la diversité des systèmes de production, dans les domaines de l'aménagement des terroirs, de la gestion des ressources (biomasses, eau...), de la gestion des exploitations (santé, zootechnie, valorisation des produits, adaptation de l'offre...). (Résumé d'auteur

Fractal/wavelet model as a deformation tool

A Fractal model equipped with detail concept like that used in wavelettransforms is introduced and used to perform global and local deformationsto objects. This fractal model based on Projected IFS attractorsallows the definition of free form fractal shapes controlled by a set ofpoints. The details concept taken from wavelet theory represents the geometric texture of the object. An approximation step is first done to fit themodel to the object, this step is formulated as a non-linear fitting problemand resolved using a modified Levenberg-Marquardt minimizationmethod. Global deformation can be achieved by moving control points orscaling and/or rotating the details extracted from the object. In the samemanner local deformation can be applied with additional control points.In this work, we focus on 2D curves

StyleDEM: a Versatile Model for Authoring Terrains

Many terrain modelling methods have been proposed for the past decades, providing efficient and often interactive authoring tools. However, they generally do not include any notion of style, which is a critical aspect for designers in the entertainment industry. We introduce StyleDEM, a new generative adversarial network method for terrain synthesis and authoring, with a versatile toolbox of authoring methods with style. This method starts from an input sketch or an existing terrain. It outputs a terrain with features that can be authored using interactive brushes and enhanced with additional tools such as style manipulation or super-resolution. The strength of our approach resides in the versatility and interoperability of the toolbox

Desertscape Simulation

International audienceWe present an interactive aeolian simulation to author hot desert scenery. Wind is an important erosion agent in deserts which, despite its importance, has been neglected in computer graphics. Our framework overcomes this and allows generating a variety of sand dunes, including barchans, longitudinal and anchored dunes, and simulates abrasion which erodes bedrock and sculpts complex landforms. Given an input time varying high altitude wind field, we compute the wind field at the surface of the terrain according to the relief, and simulate the transport of sand blown by the wind. The user can interactively model complex desert landscapes, and control their evolution throughout time either by using a varietyof interactive brushes or by prescribing events along a user-defined time-line