Painterly rendering techniques: A state-of-the-art review of current approaches

In this publication we will look at the different methods presented over the past few decades which attempt to recreate digital paintings. While previous surveys concentrate on the broader subject of non-photorealistic rendering, the focus of this paper is firmly placed on painterly rendering techniques. We compare different methods used to produce different output painting styles such as abstract, colour pencil, watercolour, oriental, oil and pastel. Whereas some methods demand a high level of interaction using a skilled artist, others require simple parameters provided by a user with little or no artistic experience. Many methods attempt to provide more automation with the use of varying forms of reference data. This reference data can range from still photographs, video, 3D polygonal meshes or even 3D point clouds. The techniques presented here endeavour to provide tools and styles that are not traditionally available to an artist. Copyright © 2012 John Wiley & Sons, Ltd

Towards photo watercolorization with artistic verisimilitude

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Video based dynamic scene analysis and multi-style abstraction.

Tao, Chenjun.Thesis (M.Phil.)--Chinese University of Hong Kong, 2008.Includes bibliographical references (leaves 89-97).Abstracts in English and Chinese.Abstract --- p.iAcknowledgements --- p.iiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Window-oriented Retargeting --- p.1Chapter 1.2 --- Abstraction Rendering --- p.4Chapter 1.3 --- Thesis Outline --- p.6Chapter 2 --- Related Work --- p.7Chapter 2.1 --- Video Migration --- p.8Chapter 2.2 --- Video Synopsis --- p.9Chapter 2.3 --- Periodic Motion --- p.14Chapter 2.4 --- Video Tracking --- p.14Chapter 2.5 --- Video Stabilization --- p.15Chapter 2.6 --- Video Completion --- p.20Chapter 3 --- Active Window Oriented Video Retargeting --- p.21Chapter 3.1 --- System Model --- p.21Chapter 3.1.1 --- Foreground Extraction --- p.23Chapter 3.1.2 --- Optimizing Active Windows --- p.27Chapter 3.1.3 --- Initialization --- p.29Chapter 3.2 --- Experiments --- p.32Chapter 3.3 --- Summary --- p.37Chapter 4 --- Multi-Style Abstract Image Rendering --- p.39Chapter 4.1 --- Abstract Images --- p.39Chapter 4.2 --- Multi-Style Abstract Image Rendering --- p.42Chapter 4.2.1 --- Multi-style Processing --- p.45Chapter 4.2.2 --- Layer-based Rendering --- p.46Chapter 4.2.3 --- Abstraction --- p.47Chapter 4.3 --- Experimental Results --- p.49Chapter 4.4 --- Summary --- p.56Chapter 5 --- Interactive Abstract Videos --- p.58Chapter 5.1 --- Abstract Videos --- p.58Chapter 5.2 --- Multi-Style Abstract Video --- p.59Chapter 5.2.1 --- Abstract Images --- p.60Chapter 5.2.2 --- Video Morphing --- p.65Chapter 5.2.3 --- Interactive System --- p.69Chapter 5.3 --- Interactive Videos --- p.76Chapter 5.4 --- Summary --- p.77Chapter 6 --- Conclusions --- p.81Chapter A --- List of Publications --- p.83Chapter B --- Optical flow --- p.84Chapter C --- Belief Propagation --- p.86Bibliography --- p.8

Utilisation du rendu expressif pour l'illustration et l'exploration de données archéologiques

National audienceLe 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

Art Directed Watercolor Shader for Non-photorealistic Rendering with a Focus on Reflections

In this research, I demonstrated that emulating painterly reflections is impossible using existing modeling, compositing and rendering software that does not provide programming capabilities. To obtain painterly reflections, we need to emulate three aspects of painterly reflections: (1) shape of reflections; (2) glossiness of reflections; and (3) colors of reflections. The first two turn out to be relatively easy. However, despite the perceived simplicity of color reproduction, the third one turned out to be hardest without developing our own proprietary tools. To demonstrate the difficulty, I have developed a shader using commercial rendering and shading software that does not provide explicit programming power. I assigned my shader as a surface material to 3D objects. Using my shader, I was able to create computer generated watercolor style renderings without reflections. My shader provide rendering effects such as diffuse, contours, specularity, shadow, and reflections. Although I can faithfully emulate non-reflected regions of given water-color paintings, I demonstrate that my shader cannot produce reflection colors that are faithful to colors of original reflections

Real-Time Stylized Rendering for Large-Scale 3D Scenes

While modern digital entertainment has seen a major shift toward photorealism in animation, there is still significant demand for stylized rendering tools. Stylized, or non-photorealistic rendering (NPR), applications generally sacrifice physical accuracy for artistic or functional visual output. Oftentimes, NPR applications focus on extracting specific features from a 3D environment and highlighting them in a unique manner. One application of interest involves recreating 2D hand-drawn art styles in a 3D-modeled environment. This task poses challenges in the form of spatial coherence, feature extraction, and stroke line rendering. Previous research on this topic has also struggled to overcome specific performance bottlenecks, which have limited use of this technology in real-time applications. Specifically, many stylized rendering techniques have difficulty operating on large-scale scenes, such as open-world terrain environments. In this paper, we describe various novel rendering techniques for mimicking hand-drawn art styles in a large-scale 3D environment, including modifications to existing methods for stroke rendering and hatch-line texturing. Our system focuses on providing various complex styles while maintaining real-time performance, to maximize user-interactability. Our results demonstrate improved performance over existing real-time methods, and offer a few unique style options for users, though the system still suffers from some visual inconsistencies

Temporally Coherent Video Stylization

International audienceThe transformation of video clips into stylized animations remains an active research topic in Computer Graphics. A key challenge is to reproduce the look of traditional artistic styles whilst minimizing distracting flickering and sliding artifacts; i.e. with temporal coherence. This chapter surveys the spectrum of available video stylization techniques, focusing on algorithms encouraging the temporally coherent placement of rendering marks, and discusses the trade-offs necessary to achieve coherence. We begin with flow-based adaptations of stroke based rendering (SBR) and texture advection capable of painting video. We then chart the development of the field, and its fusion with Computer Vision, to deliver coherent mid-level scene representations. These representations enable the rotoscoping of rendering marks on to temporally coherent video regions, enhancing the diversity and temporal coherence of stylization. In discussing coherence, we formalize the problem of temporal coherence in terms of three defined criteria, and compare and contrast video stylization using these

A shader based approach to painterly rendering

The purpose of this thesis is to develop a texture-based painterly shader that would render computer generated objects or scenes with strokes that are visually similar to paint media like watercolor, oil paint or dry media such as crayons, chalk, et cetera. This method would need an input scene in the form of three dimensional polygonal or NURBS meshes. While the structure of the meshes and the lighting in the scene would both play a crucial role in the final appearance of the scene, the painterly look will be imparted through a shader. This method, therefore, is essentially a rendering technique. Several modifiable parameters in the shader gives the user artistic freedom while overall introducing some amount of automation in the painterly rendering process