A Programmable Model for Designing Stationary 2D Arrangements

This paper introduces a programmable method for designing stationary 2D arrangements for element textures, namely textures made of small geometric elements. These textures are ubiquitous in numerous applications of computer-aided illustration. Previous methods, whether they be example-based or layout-based, lack control and can produce a limited range of possible arrangements. Our approach targets technical artists who will design an arrangement by writing a script.These scripts are using three types of operators: partitioning operators for defining the broad-scale organization of the arrangement, mapping operators for controlling the local organization of elements, and merging operators for mixing different arrangements. These operators are designed so as to guarantee a stationary result meaning that the produced arrangements will always be repetitive. We show that this simple set of operators is sufficient to reach a much broader variety of arrangements than previous methods. Editing the script leads to predictable changes in the synthesized arrangement, which allows an easy iterative design of complex structures. Finally, our operator set is extensible and can be adapted to application-dependent needs

Transfert de couleurs et colorisation guidés par la texture

National audienceCet article se concentre sur deux problèmes de manipulation de couleurs liés : le transfert de couleurs qui modifie les couleurs d'une image, et la colorisation qui ajoute des couleurs à une image en niveaux de gris. Les méthodes automatiques pour ces deux applications modifient l'image d'entrée à l'aide d'une image de référence contenant les couleurs désirées. Les approches précédentes visent rarement les deux problèmes simultanement et souffrent de deux principales limitations : les correspondances créées entre les images d'entrée et de référence sont incorrectes ou approximatives, et une mauvaise cohérence spatiale autour des structures de l'image. Dans cet article, nous proposons un pipeline unifiant les deux problèmes, basé sur le contenu texturel des images pour guider le transfert ou la colorisation. Notre méthode introduit un descripteur de textures préservant les contours de l'image, basé sur des matrices de covariance, permettant d'appliquer des transformations de couleurs locales. Nous montrons que notre approche est capable de produire des résultats comparables ou meilleurs que d'autres méthodes de l'état de l'art dans les deux applications

Discrete Texture Design Using a Programmable Approach

International audienceIn this work, we call "discrete texture" any repetitive pattern composed of small, perceivable elements. A lot of art techniques involve manual production of discrete textures, that is very expensive. We address the problem of discrete texture synthesis. Previous works introduced by-example tools: simple interfaces that allow one to draw a small texture exemplar. The tool analyses this exemplar and reproduces it on a larger scale. However, these algorithms fail to reproduce faithfully both large scale effects and local structures of elements. In contrast, our approach allows one to write the program that synthesizes the texture. We provide a set of operators that distribute points, curves or regions in the plane. We show that a large range of textures can be easily designed with our system. Additionaly, we prove that many variants of classic element distribution algorithms can be written as simple combinations of our operators

Adaptive evolution of the symbiotic gene NORK is not correlated with shifts of rhizobial specificity in the genus Medicago

<p>Abstract</p> <p>Background</p> <p>The <it>NODULATION RECEPTOR KINASE </it>(<it>NORK</it>) gene encodes a Leucine-Rich Repeat (LRR)-containing receptor-like protein and controls the infection by symbiotic rhizobia and endomycorrhizal fungi in Legumes. The occurrence of numerous amino acid changes driven by directional selection has been reported in this gene, using a limited number of messenger RNA sequences, but the functional reason of these changes remains obscure. The <it>Medicago </it>genus, where changes in rhizobial associations have been previously examined, is a good model to test whether the evolution of <it>NORK </it>is influenced by rhizobial interactions.</p> <p>Results</p> <p>We sequenced a region of 3610 nucleotides (encoding a 392 amino acid-long region of the NORK protein) in 32 <it>Medicago </it>species. We confirm that positive selection in <it>NORK </it>has occurred within the <it>Medicago </it>genus and find that the amino acid positions targeted by selection occur in sites outside of solvent-exposed regions in LRRs, and other sites in the N-terminal region of the protein. We tested if branches of the <it>Medicago </it>phylogeny where changes of rhizobial symbionts occurred displayed accelerated rates of amino acid substitutions. Only one branch out of five tested, leading to <it>M. noeana</it>, displays such a pattern. Among other branches, the most likely for having undergone positive selection is not associated with documented shift of rhizobial specificity.</p> <p>Conclusion</p> <p>Adaptive changes in the sequence of the NORK receptor have involved the LRRs, but targeted different sites than in most previous studies of LRR proteins evolution. The fact that positive selection in <it>NORK </it>tends not to be associated to changes in rhizobial specificity indicates that this gene was probably not involved in evolving rhizobial preferences. Other explanations (<it>e.g</it>. coevolutionary arms race) must be tested to explain the adaptive evolution of <it>NORK</it>.</p

Johann Friedrich Schannat erlernt die Praktiken der (kirchen-)historischen Gelehrsamkeit

Zusammenfassung: Alle Praktiken von Gelehrsamkeit stehen in Re­lation zu «epistemischen Tugenden», also einem Bezugsrahmen für den Gelehrten im Umgang mit seinem Material ebenso wie mit seiner sozialen Umgebung. Wenn diese Feststellung für alle Mit­glieder der Res publica literaria gilt, so tut sie dies in verstärktem Ausmaß für diejenigen unter ihnen, die sich bei ihrer Befassung mit Kirchengeschichte in einem institutionellen Rahmen bewegen, der ei­nige dieser Tugenden und Praktiken gleichsam in einen normativen Rang zu erheben vermag. Oft im Spannungsfeld dieser Pole angesiedelt, legen Gele­hrtenkorrespondenzen beredtes Zeugnis ab von der Erlernung und Anwendung, jedoch auch von der Ablehnung und Infragestellung solcher Praktiken und Tugenden durch die Gelehrten. Aus dieser theoretischen Perspektive bietet der vorliegenden Beitrag eine selektive Analyse der Korrespondenz von Johann Friedrich Schannat (1683–1739), einem aus Luxemburg stammenden Gelehrten im Dienst unterschiedlicher kirchlicher Würdenträger (Fulda, Worms, Prag) und damit zugleich einem «wandern­den» Kirchenhistoriker: Indem er nicht an einen archivischen oder bibliothekarischen Bestand und ebenso wenig an ein spezifisches patronales Umfeld dauerhaft gebunden war, musste Schannat sein Re­pertoire an Praktiken und Tugenden stets neu ak­tualisieren. Je nach Position des brieflichen Gegenü­bers konnten diesen unterschiedliche intellektuelle und soziale Ausprägungen zukommen, wie an den Briefwechseln Schannats mit dem Freiherrn Wil­helm von Crassier, dem Mauriner Edmond Martène und dem österreichischen Benediktinergelehrten Bernhard Pez deutlich wird. Abstract: All practices of erudition are related to «epis­temic virtues», meaning a reference frame for scholars defining how to interact with their objects and their social environment. If this as­sumption holds true for all members of the Res publica literaria, it does so even more for those who, in dealing with ecclesiastical history, are part of an institutional framework that elevates some of those practices and virtues to a norma­tive level. Often situated between these poles, learned correspondences testify to the learning and application, but also to the refusal and ques­tioning of such virtues and practices. Viewed from this theoretical basis, the presented paper offers a selective analysis of the corresponden­ce of Johann Friedrich Schannat (1683–1739), a scholar from Luxembourg who entered the ser­vices of various ecclesiastical dignitaries (Fulda, Worms, Prague), thereby becoming an «itine­rant» church historian: Not bound by long-las­ting ties to a specific archive or library, or to an individual environment of patronage, Schannat was required to constantly re-adapt his reper­toire of practices and virtues. Depending on the position of the correspondence partner, his framework of reference could assume different intellectual and social characteristics, as illus­trated by his correspondences with the Baron Crassier, the Maurist Martène and the Austrian Benedictine scholar Bernhard Pez. Stichwörter: Frühe Neuzeit, Res publica literaria, Gelehrtenkorres­pondenz, Kirchengeschichtsschreibung, Historiogra­phiegeschichte, Historische Epistemologie, Epistemische Tugenden. Key words: Early modern history, res publica literaria, eru­dite correspondence, ecclesiastical historiogra­phy, history of historiography, historical episte­mology, epistemic virtues

Microsatellite diversity and broad scale geographic structure in a model legume: building a set of nested core collection for studying naturally occurring variation in Medicago truncatula

BACKGROUND: Exploiting genetic diversity requires previous knowledge of the extent and structure of the variation occurring in a species. Such knowledge can in turn be used to build a core-collection, i.e. a subset of accessions that aim at representing the genetic diversity of this species with a minimum of repetitiveness. We investigate the patterns of genetic diversity and population structure in a collection of 346 inbred lines representing the breadth of naturally occurring diversity in the Legume plant model Medicago truncatula using 13 microsatellite loci distributed throughout the genome. RESULTS: We confirm the uniqueness of all these genotypes and reveal a large amount of genetic diversity and allelic variation within this autogamous species. Spatial genetic correlation was found only for individuals originating from the same population and between neighbouring populations. Using a model-based clustering algorithm, we identified four main genetic clusters in the set of individuals analyzed. This stratification matches broad geographic regions. We also identified a set of "admixed" individuals that do not fit with this population structure scheme. CONCLUSION: The stratification inferred is discussed considering potential historical events like expansion, refuge history and admixture between neighbouring groups. Information on the allelic richness and the inferred population structure are used to build a nested core-collection. The set of inbred lines and the core collections are publicly available and will help coordinating efforts for the study of naturally occurring variation in the growing Medicago truncatula community

Texture Transfer Based on Texture Descriptor Variations

In this report, we tackle the problem of image-space texture transfer which aims to modify an object or surface material by replacing its input texture by another reference texture. The main challenge of texture transfer is to successfully reproduce the reference texture patterns while preserving the input texture variations due to its environment such as illumination or shape variations. We propose to use a texture descriptor composed of local luminance and local gradients orientation and magnitude to characterize the input texture variations. We then introduce a guided texture synthesis algorithm to synthesize a texture resembling the reference texture with the input texture variations. The main contribution of our algorithm is its ability to locally deform the reference texture according to local texture descriptors in order to better reproduce the input texture variations. We show that our approach is able to produce results comparable with current state-of-the-art approaches but with fewer user inputs.Dans ce rapport, nous nous intéressons au transfert de texture en espace imagequi consiste à modifier le matériau d’un objet ou d’une surface en remplaçant sa texture d’entréepar une texture de référence. La principale difficulté du transfert de texture est d’arriver àreproduire les motifs de la texture de référence, tout en préservant les variations de la textured’entrée introduites par son environnement comme des variations de forme ou d’illumination.Nous proposons d’utiliser un descripteur de texture composé de la luminance locale ainsi que del’orientation et l’amplitude locale des gradients afin de caractériser les variations de la textured’entrée. Nous introduisons ensuite un algorithme de synthèse de texture guidé afin de synthétiserune texture ressemblant à la référence mais préservant les variations de la texture d’entrée. Laprincipale contribution de cet algorithme est sa capacité à déformer la texture de référencelocalement en fonction du descripteur de texture. Cette approche permet d’obtenir des résultatscomparables à l’état de l’art, mais nécessitant moins d’informations de la part de l’utilisateur

Transfert de couleurs et colorisation guidés par la texture

National audienceCet article se concentre sur deux problèmes de manipulation de couleurs liés : le transfert de couleurs qui modifie les couleurs d'une image, et la colorisation qui ajoute des couleurs à une image en niveaux de gris. Les méthodes automatiques pour ces deux applications modifient l'image d'entrée à l'aide d'une image de référence contenant les couleurs désirées. Les approches précédentes visent rarement les deux problèmes simultanement et souffrent de deux principales limitations : les correspondances créées entre les images d'entrée et de référence sont incorrectes ou approximatives, et une mauvaise cohérence spatiale autour des structures de l'image. Dans cet article, nous proposons un pipeline unifiant les deux problèmes, basé sur le contenu texturel des images pour guider le transfert ou la colorisation. Notre méthode introduit un descripteur de textures préservant les contours de l'image, basé sur des matrices de covariance, permettant d'appliquer des transformations de couleurs locales. Nous montrons que notre approche est capable de produire des résultats comparables ou meilleurs que d'autres méthodes de l'état de l'art dans les deux applications

A Programmable Model for Designing Stationary 2D Arrangements

This paper introduces a programmable method for designing stationary 2D arrangements for element textures, namely textures made of small geometric elements. These textures are ubiquitous in numerous applications of computer-aided illustration. Previous methods, whether they be example-based or layout-based, lack control and can produce a limited range of possible arrangements. Our approach targets technical artists who will design an arrangement by writing a script.These scripts are using three types of operators: partitioning operators for defining the broad-scale organization of the arrangement, mapping operators for controlling the local organization of elements, and merging operators for mixing different arrangements. These operators are designed so as to guarantee a stationary result meaning that the produced arrangements will always be repetitive. We show that this simple set of operators is sufficient to reach a much broader variety of arrangements than previous methods. Editing the script leads to predictable changes in the synthesized arrangement, which allows an easy iterative design of complex structures. Finally, our operator set is extensible and can be adapted to application-dependent needs

A workflow for designing stylized shading effects

In this report, we describe a workflow for designing stylized shading effects on a 3D object, targeted at technical artists. Shading design, the process of making the illumination of an object in a 3D scene match an artist vision, is usually a time-consuming task because of the complex interactions between materials, geometry, and lighting environment. Physically based methods tend to provide an intuitive and coherent workflow for artists, but they are of limited use in the context of non-photorealistic shading styles. On the other hand, existing stylized shading techniques are either too specialized or require considerable hand-tuning of unintuitive parameters to give a satisfactory result. Our contribution is to separate the design process of individual shading effects in three independent stages: control of its global behavior on the object, addition of procedural details, and colorization. Inspired by the formulation of existing shading models, we expose different shading behaviors to the artist through parametrizations, which have a meaningful visual interpretation. Multiple shading effects can then be composited to obtain complex dynamic appearances. The proposed workflow is fully interactive, with real-time feedback, and allows the intuitive exploration of stylized shading effects, while keeping coherence under varying viewpoints and light configurations. Furthermore, our method makes use of the deferred shading technique, making it easily integrable in existing rendering pipelines.Dans ce rapport, nous décrivons un outil de création de modèles d'illumination adapté à la stylisation de scènes 3D. Contrairement aux modèles d'illumination photoréalistes, qui suivent des contraintes physiques, les modèles d'illumination stylisés répondent à des contraintes artistiques, souvent inspirées de la représentation de la lumière en illustration. Pour cela, la conception de ces modèles stylisés est souvent complexe et coûteuse en temps. De plus, ils doivent produire un résultat cohérent sous une multitude d'angles de vue et d'éclairages. Nous proposons une méthode qui facilite la création d'effets d'illumination stylisés, en décomposant le processus en trois parties indépendantes: contrôle du comportement global de l'illumination, ajout de détails procéduraux, et colorisation.Différents comportements d'illumination sont accessibles à travers des paramétrisations, qui ont une interprétation visuelle, et qui peuvent être combinées pour obtenir des apparences plus complexes. La méthode proposée est interactive, et permet l'exploration efficace de modèles d'illumination stylisés. La méthode est implémentée avec la technique de deferred shading, ce qui la rend facilement utilisable dans des pipelines de rendu existants