Dynamic Stylized Shading Primitives

Honorable Mention in RenderingInternational audienceShading 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

Interactive toon shading using mesh smoothing

Toon shading mimics the style of few colour bands and hence offers an effective way to convey the cartoon-style rendering. Despite an increasing amount of research on toon shading, little research has been reported on generation of toon shading style with more simplicity. In this paper, we present a method to create a simplified form of toon shading using mesh smoothing from 3D objects. The proposed method exploits the Laplacian smoothing to emphasise the simplicity of 3D objects. Motivated by simplified form of Phong lighting model, we create non-photorealistic style capable of enhancing the cartoonish appearance. An enhanced toon shading algorithm is applied on the simple 3D objects in order to convey more simple visual cues of tone. The experimental result reveals the ability of proposed method to produce more cartoonish simplistic effects

Contrôle artistique par édition de la propagation des rayons en photon mapping

National audiencePhysically based rendering with global illumination effects, has become a standard technique for high quality computer generated imagery. Nonetheless, being able to control the resulting picture so that it corresponds to the artist vision is still a tedious trial and error process. We introduce a path selection and edition metaphor, to give the artist a precise control over the final rendering without modifying the scene parameters. Starting from the identification of a lighting feature and its transcription in a path space regular expression, the proposed approach consists in selecting the corresponding light transport paths in 3D space and transforms them according to user defined operations.These operations affect both the geometry and the color spectrum of the paths.We demonstrate the wide range of control it permits on various lighting features, from low frequency color bleeding to high frequency caustics as well as view-dependent reflections.e rendu produisant des effets d'éclairement global est devenu un standard pour la synthèse d'image de haute qualité.Néanmoins, les graphistes ne peuvent éditer les images générées informatiquement qu'au prix d'un travail long et fastidieux sur la définition des sources de lumières et des matériaux de la scène 3D.Nous proposons une approche d'édition qui donne un contrôle précis sur le rendu final, sans modifier les paramètres de la scène 3D.À partir de l'identification d'un effet lumineux définie par une syntaxe d'interaction, l'approche consiste à sélectionner des chemins de transport lumineux et de les transformer suivant des opérations définies par le graphiste.Ces opérations sont des transformations sur la géométrie du transport lumineux ainsi que sur les spectres transportés par les chemins.Nous montrons la large gamme d'éditions que notre approche permet sur divers effets lumineux, allant des variations basses fréquences de diffusion indirecte de couleur, jusqu'aux variations hautes fréquences typiques des caustiques

Interactive non-photorealistic rendering

Due to increasing demands of artistic style with Interactive Rate, we propose this review paper as a starting point for any person interested in researching of interactive non-photorealistic rendering. As a simple yet effective means of visual communication, interactive non-photorealistic rendering generates images that are closer to human-drawn than are created by traditional computer graphics techniques with more expressing meaningful visual information. This paper presents taxonomy of interactive non-photorealistic rendering techniques which developed over the past two decades, structured according to the design characteristics and behavior of each technique. Also, it covers the most important algorithms in interactive stylized shade and line drawing, and separately discussing their advantages and disadvantages. The review then concludes with a discussion of the main issues and technical challenges for Interactive Non-Photorealistic Rendering techniques. In addition, this paper discusses the effect of modified phong shading model in order to create toon shading appearance

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