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

Direct Shader Sampling in Painterly Rendering for Animation

We present a technique for generating stroke parameters in particlebased painterly rendering algorithms that guarantees temporal coherence in animation through directly sampling shaders. To determine the appropriate color for a brush stroke, techniques like [Meier 1996] render the scene into reference pictures using traditional techniques. This reference picture is then queried by applying the camera transform to the particle’s position. This transform will not always map to the correct pixel which can lead to noticeable temporal discontinuities when there is a significant color difference between two neighboring pixels. When a stroke particle lies on the edge of an object, the brush stroke will sometimes flicker between the two neighboring colors. Previously, as described in [Meier 1996], scenes would be broken up into different layers, and image processing effects were applied to reference pictures to ensure that the right color is sampled. Our method requires no post processing effects to ensure temporal coherence around these edge cases

Expressive Animated Character Sequences Using Knowledge-Based Painterly Rendering

We propose a technique to enhance emotionalexpressiveness in games and animations. Artists have usedcolors and painting techniques to convey emotions in theirpaintings for many years. Moreover, researchers have foundthat colors and line properties affect users\u27 emotions. Wepropose using painterly rendering for character sequencesin games and animations with a knowledge-based approach. This technique is especially useful for parametric facial sequences. We introduce two parametric authoring tools foranimation and painterly rendering and a method to integrate them into a knowledge-based painterly rendering system. Furthermore, we present the results of a preliminarystudy on using this technique for facial expressions in stillimages. The results of the study show the effect of different color palettes on the intensity perceived for an emotionby users. The proposed technique can provide the animatorwith a depiction tool to enhance the emotional content of acharacter sequence in games and animations

A Process to Create Dynamic Landscape Paintings Using Barycentric Shading with Control Paintings

In this work, we present a process that uses a Barycentric shading method to create dynamic landscape paintings that change based on the time of day. Our process allows for the creation of dynamic paintings for any time of the day using simply a limited number of control paintings. To create a proof of concept, we have used landscape paintings of Edgar Payne, one of the leading landscape painters of the American West. His specific style of painting that blends Impressionism with the style of other painters of the AmericanWest is particularly appropriate for the demonstration of the power of our Barycentric shading method

A painterly approach to 3D graphics

This paper is a review and exploration of the work over the last ten years of Light Years Projects, a collaboration between Jeremy Gardiner and myself. It covers in particular how I have explored the notion of a painterly approach to real-time 3D computer graphics. It deals with the tensions, temptations and opportunities that lie in the area where landscape painting crosses with technology, concluding with some of the lessons I have learnt

Towards Simulation of Handmade Painterly Animation

International audienceThis poster presents research in progress towards the simulation of handmade painterly animation. As researches on painterly animation mostly focus on temporal coherence, the generation of an animation that could have been done by hand remains an open challenging problem. To produce an hand made painterly animation, the artist paints on a retro-lighted glass canvas. He creates successive frames one over the other. The artist erase, smears and adds paint to produce each frame. We propose to render painterly animations with a visual aspect tending towards hand made results.To this end, we combines two techniques: an automatic strokes generator and a paint simulator. We observe that previous approaches could not adapt as-is to our goals for the two following reasons:Paint appearance in painterly animation is back lighted, most of paint contrast comes from paint thickness which is usually not compute by paint simulation approaches. Automatic strokes generation make the assumption that a stroke covers underlying strokes without having thickness accumulation, in our case paint thickness quickly increase if we do not apply special treatment. We also investigate new kind of strokes that are only possible with a paint simulation approach as smear and erase strokes

Stroke Based Painterly Rendering

International audienceMany traditional art forms are produced by an artist sequentially placing a set of marks, such as brush strokes, on a canvas. Stroke based Rendering (SBR) is inspired by this process, and underpins many early and contemporary Artistic Stylization algorithms. This Chapter outlines the origins of SBR, and describes key algorithms for placement of brush strokes to create painterly renderings from source images. The chapter explores both local greedy, and global optimization based approaches to stroke placement. The issue of creative control in SBR is also briefly discussed

Exploring a Parameterized Portrait Painting Space

We overview our interdisciplinary work building parameterized knowledge domains and their authoring tools that allow for expression systems which move through a space of painterly portraiture. With new computational systems it is possible to conceptually dance, compose and paint in higher level conceptual spaces. We are interested in building art systems that support exploring these spaces and in particular report on our software-based artistic toolkit and resulting experiments using parameter spaces in face based new media portraiture. This system allows us to parameterize the open cognitive and vision-based methodology that human artists have intuitively evolved over centuries into a domain toolkit to explore aesthetic realizations and interdisciplinary questions about the act of portrait painting as well as the general creative process. These experiments and questions can be explored by traditional and new media artists, art historians, cognitive scientists and other scholars

Shading with Painterly Filtered Layers: A Process to Obtain Painterly Portraits

In this thesis, I study how color data from different styles of paintings can be extracted from photography with the end result maintaining the artistic integrity of the art style and having the look and feel of skin. My inspiration for this work came from the impasto style portraitures of painters such as Rembrandt and Greg Cartmell. I analyzed and studied the important visual characteristics of both Rembrandt’s and Cartmell’s styles of painting.These include how the artist develops shadow and shading, creates the illusion of subsurface scattering, and applies color to the canvas, which will be used as references to help develop the final renders in computer graphics. I also examined how color information can be extracted from portrait photography in order to gather accurate dark, medium, and light skin shades. Based on this analysis, I have developed a process for creating portrait paintings from 3D facial models. My process consists of four stages: (1) Modeling a 3D portrait of the subject, (2) data collection by photographing the subjects, (3) Barycentric shader development using photographs, and (4) Compositing with filtered layers. My contributions has been in stages (3) and (4) as follows: Development of an impasto-style Barycentric shader by extracting color information from gathered photographic images. This shader can result in realistic looking skin rendering. Development of a compositing technique that involves filtering layers of images that correspond to different effects such as diffuse, specular and ambient. To demonstrate proof-of-concept, I have created a few animations of the impasto style portrait painting for a single subject. For these animations, I have also sculpted high polygon count 3D model of the torso and head of my subject. Using my shading and compositing techniques, I have created rigid body animations that demonstrate the power of my techniques to obtain impasto style portraiture during animation under different lighting conditions