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Home | Research | Projects/softs | Teaching |
| Implicit Brushes for Stylized Line-Based Rendering | |
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Romain Vergne, David Vanderhaeghe, Jiazhou Chen, Pascal Barla, Xavier Granier, Christophe Schlick Computer Graphics Forum (Proceedings of Eurographics 2011) - 2011 Best paper (3rd) We introduce a new technique called Implicit Brushes to render animated 3D scenes with stylized lines in real-time with temporal coherence. An Implicit Brush is defined at a given pixel by the convolution of a brush footprint along a feature skeleton; the skeleton itself is obtained by locating surface features in the pixel neighborhood. Features are identified via image-space fitting techniques that not only extract their location, but also their profile, which permits to distinguish between sharp and smooth features. Profile parameters are then mapped to stylistic parameters such as brush orientation, size or opacity to give rise to a wide range of line-based styles. [PAPER] |
| Improving Shape Depiction under Arbitrary Rendering | |
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Romain Vergne, Romain Pacanowski, Pascal Barla, Xavier Granier, Christophe Schlick IEEE. Transaction on Visualization and Computer Graphics. 2011 Based 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. [PAPER] |
| Light Warping for Enhanced Shape Depiction | |
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Romain Vergne, Romain Pacanowski, Pascal Barla, Xavier Granier, Christophe Schlick ACM Transaction on Graphics - Proceedings of SIGGRAPH 2009 Front cover Recent research on the human visual system shows that our perception of object shape relies in part on compression and stretching of the reflected lighting environment onto its surface. We use this property to enhance the shape depiction of 3D objects by locally warping the environment lighting around main surface features. Contrary to previous work, which require specific illumination, material characteristics and/or stylization choices, our approach enhances surface shape without impairing the desired appearance. Thanks to our novel local shape descriptor, salient surface features are explicitly extracted in a view-dependent fashion at various scales without the need of any pre-process. We demonstrate our system on a variety of rendering settings, using object materials ranging from diffuse to glossy, to mirror or refractive, with direct or global illumination, and providing styles that range from photorealistic to non-photorealistic. The warping itself is very fast to compute on modern graphics hardware, enabling real-time performance in direct illumination scenarios. [PAPER] |
| Dynamic Stylized Shading Primitives | |
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David Vanderhaeghe, Romain Vergne, Pascal Barla, William Baxter NPAR '11:Proceedings of the 8th International Symposium on Non-Photorealistic Animation and Rendering (2011) 99-104 Honorable Mention in Rendering Shading appearance in illustrations, comics and graphic novels is designed to convey illumination, material and surface shape characteristics at once. Moreover, shading may vary depending on different configurations of surface distance, lighting, character expressions, timing of the action, to articulate storytelling or draw attention to a part of an object. In this paper, we present a method that imitates such expressive stylized shading techniques in dynamic 3D scenes, and which offers a simple and flexible means for artists to design and tweak the shading appearance and its dynamic behavior. The key contribution of our approach is to seamlessly vary appearance by using a combination of shading primitives that take into account lighting direction, material characteristics and surface features. We demonstrate their flexibility in a number of scenarios: minimal shading, comics or cartoon rendering, glossy and anisotropic material effects; including a variety of dynamic variations based on orientation, timing or depth. Our prototype implementation combines shading primitives with a layered approach and runs in real-time on the GPU. [PAPER] |
| Radiance Scaling for Versatile Surface Enhancement | |
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Romain Vergne, Romain Pacanowski, Pascal Barla, Xavier Granier, Christophe Schlick I3D '10: Proc. symposium on Interactive 3D graphics and games - 2010 Best paper (Honorable mention), back cover We present a novel technique called Radiance Scaling for the depiction of surface shape through shading. It adjusts reflected light intensities in a way dependent on both surface curvature and material characteristics. As a result, diffuse shading or highlight variations become correlated to surface feature variations, enhancing surface concavities and convexities. This approach is more versatile compared to previous methods. First, it produces satisfying results with any kind of material: we demonstrate results obtained with Phong and Ashikmin BRDFs, Cartoon shading, sub-Lambertian materials, and perfectly reflective or refractive objects. Second, it imposes no restriction on lighting environment: it does not require a dense sampling of lighting directions and works even with a single light. Third, it makes it possible to enhance surface shape through the use of precomputed radiance data such as Ambient Occlusion, Prefiltered Environment Maps or Lit Spheres. Our novel approach works in real-time on modern graphics hardware and is faster than previous techniques. [PAPER] |
| Apparent relief: a shape descriptor for stylized shading | |
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Romain Vergne, Pascal Barla, Xavier Granier, Christophe Schlick NPAR '08: Proceedings of the 6th international symposium on Non-photorealistic animation and rendering - 2008 Back cover Shape depiction in non-photorealistic rendering of 3D objects has mainly been concerned with the extraction of contour lines, which are generally detected by tracking the discontinuities of a given set of shape features varying on the surface and/or the picture plane. In this paper, we investigate another approach: the depiction of shape through shading. This technique is often used in scientific illustration, comics, cartoon animation and various other artwork. A common method consists in indirectly adapting light positions to reveal shape features; but it quickly becomes impractical when the complexity of the object augments. In contrast, our approach is to directly extract a set of shape cues that are easily manipulated by a user and re-introduced during shading. The main problem raised by such an approach is that shape cues must be identified in a continuous way in image space, as opposed to line-based techniques. Our solution is a novel view-dependent shape descriptor called Apparent Relief, which carries pertinent continuous shape cues for every pixel of an image. It consists of a combination of object- and image-space attributes. Such an approach provides appealing properties: it is simple to manipulate by a user, may be applied to a vast range of styles, and naturally brings levels-of-detail functionalities. It is also simple to implement, and works in real-time on modern graphics hardware. [PAPER] |
| Shading with Apparent Relief | |
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Romain Vergne, Pascal Barla, Xavier Granier, Christophe Schlick ACM Siggraph 2008 - Talk Program - aug 2008 Shape depiction is an important dimension of image creation. For example, techniques are used to remove ambiguities in scientific illustrations, or to create more legible representations in paintings and drawings. Previous approaches focus on a set body of techniques: line-based rendering. Such techniques generate some shape cues to depict the object characteristics that correspond to discontinuities of shape features. Many artists rather depict an object's shape through shading. They have to use other kinds of shape cues that correspond to continuous variations of shape features to convey more subtle information about shape and integrate it seamlessly into conventional lighting. Instead of detecting sharp discontinuities as in line-based rendering, we thus seek a set of continuous cues that have to be defined for each pixel of an image. To this end, we introduce an intermediate representation that we call Apparent Relief to assist the user. It is a view-dependent shape descriptor, from which continuous shape cues are easily extracted, and which gives rise to stylized shading-based shape depictions. By construction, it is free of temporal coherence artifacts and naturally leads to automatic Levels-of-Detail (LOD) effects. Our approach is simple to implement, runs in real-time on modern graphics hardware, and allows a user selection of features. We illustrate its potential using several shading styles. [PAPER] |
| La numérisation et la visualisation 3D de l’épitaphe de Costaulus | |
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Romain Vergne, Pascal Mora, Frédéric Boutoulle Fabrique d'une ville médiévale. Saint Emilion au moyent âge. 2011 |
| L'epitaphe, le lazer, et l'image 3D. La numérisation de l'épitaphe de Costaulus à Saint Emilion (Gironde). | |
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Romain Vergne, Pascal Mora, Frédéric Boutoulle L'épitaphe médiévale. Dossiers de l'archéologie 2011. (A paraître) |
| Stylisation d'objets éclairés par des cartes d'environnement HDR | |
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Romain Vergne, Xavier Granier Actes des 20èmes Journées de l'Association Française d'Informatique Graphique (AFIG) - 2007 In this paper, we introduce a pipeline for an interactive and stylized rendering of High-Dynamic Range (HDR) environment-mapped objects. By using stylization on HDR images, the quality, the segmentation and the details are improved. Furthermore, this pipeline allows an easy combination of 2D stylization (on the environment map, and on the images) and 3D stylization (on the object). Based on this pipeline, we present new interactive styles that illustrate our approach. Through these styles, we detail the purpose and the action of each rendering step, in order to show its flexibility and to allow the reader the implementation of new styles. Dans cet article, nous introduisons un pipeline de rendu permettant de styliser de manière interactive des objets éclairés par des cartes d’environnement à grande dynamique (High-Dynamic Range ou HDR). L’utilisation d’images HDR permet d’améliorer la qualité de certains traitements, comme les segmentations ou l’extraction des détails. De plus, cette architecture permet de combiner facilement des stylisations 2D (sur la carte d’environnement et sur les images) et 3D (sur les objets). Les nouveaux styles que nous présentons sont basés sur ce pipeline et illustrent la flexibilité de notre approche. 1. [PAPER] |
| Utilisation du rendu expressif pour l'illustration et l'exploration de données archéologiques | |
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Romain Vergne, Adrien Bousseau, Joëlle Thollot, David Vanderhaeghe, Pascal Barla, Xavier Granier Virtual Retrospect 2007 : Archéologie et Réalité Virtuelle - 2007 Le rendu expressif est une branche relativement jeune de la synthèse d'images qui s'intéresse non pas à créer des images qui sont le résultat de simulations de phénomènes physiques réalistes, mais qui tend à communiquer visuellement des informations sur les objets représentés par le biais de styles variés (dessin, aquarelle, etc). Ce type de rendu semble particulièrement adapté au domaine de l'archéologie pour deux raisons : il permet d'illustrer les hypothèses de reconstruction 3D archéologiques sans pour autant biaiser l'interprétation par une représentation trop réaliste et peut aussi apporter une méthode visuelle intuitive d'exploration de données archéologiques. Dans cet exposé, nous allons tout d'abord présenter les travaux que nous avons réalisé par le passé portant sur la création d'illustrations (effets de papier, aquarelle). Puis nous allons introduire les aspects du rendu expressif qui permettraient l'exploration sémantique de données archéologiques. [PAPER] |
| Expressing Rendering for Interactive Applications | |
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Adrien Bousseau, Pascal Barla, Xavier Granier, Joëlle Thollot, David Vanderhaeghe, Romain Vergne Game Developper Conference (Lyon, 2007) [PAPER] |
| Communication expressive de la forme au travers de l'éclairement et du rendu au trait | |
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Romain Vergne PhD. thesis (in french) - 2010 Le rendu expressif a pour objectif de développer des algorithmes qui donnent la possibilité aux utilisateurs de créer des images artistiques. Il permet non-seulement de reproduire des styles traditionnels, mais surtout de communiquer un message spécifique avec un style qui lui correspond. Dans ce manuscrit, nous proposons de nouvelles solutions pour réintroduire la forme, souvent masquée dans les images réalistes. Nous montrons tout d'abord comment extraire les informations de surface pertinentes sur des objets 3D dynamiques, en nous basant sur les caractéristiques du système visuel humain, de sorte à obtenir des informations qui fournissent des niveaux de détail automatiques tout en prenant le point de vue en compte. Dans un dexième temps, nous utilisons ces données extraites à la surface des objets 3D pour les intégrer en temps réel dans des styles variés, allant du rendu minimaliste noir et blanc au dessin au trait, en passant par des résultats réalistes. [THESIS] |
