A scientific network serving the uses of 3D humanities

International audienceThe 3D Consortium of the TGIR Huma-Num has been created based on the observation that there are many initiatives around 3D for the Digital Humanities without real coordination between them. The proliferation of initiatives makes the task difficult and only a consortium-type organization can bring together forces in order to define standardized solutions. The difficulty is increased by the fact that we are dealing with multiple domains, combining science and technology with the humanities. The  aim of the consortium is to facilitate discussions by putting together a maximum of research groups that integrate the use of 3D digital data in their scientific practices, to develops tools for acquisition, visualization, interpretation and preservation of data for the Humanities. The consortium is therefore willing to develop synergies between national Humanities and 3D disciplines in order to: share experiences; edit recommendations in terms of methodology, standards and formats; identify the specific needs of Digital Humanities and link them to the rapid evolution of 3D technologies; develop common tools and platforms; bring French experiences into international works (Parthenos, Dariah, ARIADNE); (vii) disseminate all this information as widely as possible, among academics, industry and administrations

Gestion de la complexité géométrique dans le calcul d'éclairement pour la présentation publique de scènes archéologiques complexes

International audienceFor cultural heritage, more and more 3D objects are acquired using 3D scanners [Levoy 2000]. The resulting objects are very detailed with a large visual richness but their geometric complexity requires specific methods to render them. We first show how to simplify those objects using a low-resolution mesh with its associated normal maps [Boubekeur 2005] which encode details. Using this representation, we show how to add global illumination with a grid-based and vector-based representation [Pacanowski 2005]. This grid captures efficiently low-frequency indirect illumination. We use 3D textures (for large objects) and 2D textures (for quasi-planar objects) for storing a fixed set of irradiance vectors. These grids are built during a preprocessing step by using almost any existing stochastic global illumination approach. During the rendering step, the indirect illumination within a grid cell is interpolated from its associated irradiance vectors, resulting in a smooth everywhere representation. Furthermore, the vector-based representation offers additional robustness against local variations of geometric properties of the scene.Pour l’étude du patrimoine, de plus en plus d’objets 3D sont acquis par le biais de scanners 3D [Levoy 2000]. Les objets ainsi acquis contiennent de nombreux détails et fournissent une très grande richesse visuelle. Mais pour les afficher, leur très grande complexité géométrique nécessite l’utilisation d’algorithmes spécifiques. Nous montrons ici comment simplifier ces objets par un maillage de faible résolution et une collection de cartes de normales [Boubekeur 2005] pour préserver les détails. Avec cette représentation, nous montrons comment il est possible de calculer un éclairement réaliste à l’aide d’une grille et de données vectorielles [Pacanowski 2005]. Cette grille permet de capturer efficacement les basses fréquences d’un éclairement indirect. Nous utilisons des textures 3D (pour des gros objets) et potentiellement des textures 2D (pour les objets quasi-plans) afin de stocker un nombre prédéterminé de vecteurs d’irradiance. Ces grilles sont calculées au cours d’un pré-calcul à l’aide de n’importe quelle méthode stochastique de calcul d’éclairement global. Pour l’affichage, l’éclairement indirect dû à la grille est interpolé au sein de la cellule associée à la position courante, fournissant ainsi une représentation continue. De plus, cette approche vectorielle permet une plus grande robustesse aux variations locales des propriétés géométriques de la scène

Triangulation of uniform particle systems: its application to the implicit surface texturing

Particle systems, as originally presented by Witkin and Heckbert [32], offer an elegant solution to sample implicit surfaces of arbitrary genus, while providing an extremely regular distribution of samples over the surface. In this paper, we present an ef cient technique that uses particle systems to rapidly generate a triangular mesh over an implicit surface, where each triangle is almost equilateral. The major advantage of such a triangulation is that it minimizes the deformations between the mesh and the underlying implicit surface. We exploit this property by using few triangular texture samples mapped in a non-periodic fashion as presented by Neyret and Cani [16]. The result is a pattern-based texturing method that maps homogeneous non-periodic textures to arbitrary implicit surfaces, with almost no deformation

3D as a Service for Cultural Heritage

International audience3D is becoming a recognized tool for research in Cultural Heritage. In this presentation, based on the work of the MANAO team-project, of the Archeovision research laboratory and of the 3D Consortium for Human and Social Sciences, we will try to demonstrate potential joint researches on acquisition, analyse, visualization and archiving

Convergence Real-Virtual thanks to Optics & Computer Sciences

International audienceCurrently, a large trend is the co-designed of hybrid systems that combined optical and digital components. Such systems may help to reach a real convergence of real and virtual worlds (a perfect augmented reality of augmented virtuality). We will illustrate this concept by some of the recent work done inside the MANAO team-project

Au-delà de l'imagerie traditionnelle: Intégration optique et informatique

National audienceOutils optiques et informatiques pour aller au-delà de l'imagerie traditionnelle. Ces 15 dernières années ont permis de revoir la manière dont on considère un capteur. Il n'est plus qu'une seule grille régulière de couleur, mais il permet d'aller chercher des informations radiométriques, et capturer des champs lumineux. Dans ce cours, nous présenterons un tour d'horizon rapide des techniques utilisées, mais aussi des réflexions que cela impose sur notre manière de voire la capture et la génération d'images dans notre domaine scientifique

Le service militaire et l'insertion professionnelle des jeunes suivant leur niveau d'étude : les leçons de la suspension de la conscription.

Cet article utilise la suspension de la conscription en France pour évaluer l'effet causal du service national sur différents aspects de l'insertion professionnelle des jeunes. Deux aspects novateurs sont plus particulièrement privilégiés: l'hétérogénéité des effets du traitement selon le niveau de sortie des études et l'influence du service national sur la durée cumulée des épisodes d'emploi. Les résultats obtenus révèlent une forte hétérogénéité des rendements de la conscription. Les rendements salariaux sont positifs pour les jeunes sortants sans diplôme du système scolaire et ceux de niveau BAC. Ils sont le plus souvent non significatifs pour les autres. Ces rendements positifs s'expliquent à la fois par la faible ampleur de la perte d'expérience professionnelle - la durée cumulée des épisodes d'emploi diminue peu et même augmente pour les non diplômés - et par un impact positif sur les premiers salaires.Conscription, effet de traitement, insertion professionnelle

Improving Shape Depiction under Arbitrary Rendering

International audienceBased on the observation that shading conveys shape information through intensity gradients, we present a new technique called Radiance Scaling that modifies the classical shading equations to offer versatile shape depiction functionalities. It works by scaling reflected light intensities depending on both surface curvature and material characteristics. As a result, diffuse shading or highlight variations become correlated to surface feature variations, enhancing concavities and convexities. The first advantage of such an approach is that it produces satisfying results with any kind of material for direct and global illumination: we demonstrate results obtained with Phong and Ashikmin-Shirley BRDFs, Cartoon shading, sub-Lambertian materials, perfectly reflective or refractive objects. Another advantage is that there is no restriction to the choice of lighting environment: it works with a single light, area lights, and inter-reflections. Third, it may be adapted to enhance surface shape through the use of precomputed radiance data such as Ambient Occlusion, Prefiltered Environment Maps or Lit Spheres. Finally, our approach works in real-time on modern graphics hardware making it suitable for any interactive 3D visualization

Control on Color Reflection Behavior

Nowadays, most of the computation of a rendering system is done in color space. Thus, the whole process, from acquisition (with a digital camera) and modelisation to display (on CRT/LCD displays) is color-based. Unfortunately, the reflection of a light on a surface is based on an approximation which can reduce the preservation of the color appearance. In this report, we present a new approach for color-based reflection that introduces a low overhead for an easy integration in current rendering systems. This approach allows also an easier control on the reflection behavior. In this report, we present also some possible applications, including global illumination, simple relighting and hardware rendering

A Final Reconstruction Approach for a Unified Global Illumination Algorithm

International audienceIn the past twenty years, many algorithms have been proposed to compute global illumination in synthetic scenes. Typically, such approaches can deal with specific lighting configurations, but often have difficulties with others. In this article, we present a final reconstruction step for a novel unified approach to global illumination, that automatically detects different types of light transfer and uses the appropriate method in a closely-integrated manner. With our approach, we can deal with difficult lighting configurations such as indirect nondiffuse illumination. The first step of this algorithm consists in a view-independent solution based on hierarchical radiosity with clustering, integrated with particle tracing. This first pass results in solutions containing directional effects such as caustics, which can be interactively rendered. The second step consists of a view-dependent final reconstruction that uses all existing information to compute higher quality, ray-traced images