Artistic Surface Rendering Using Layout of Text

An artistic rendering method of free-form surfaces with the aid of half-toned text that is laid-out on the given surface is presented. The layout of the text is computed using symbolic composition of the free-form parametric surface  S(u, v)  with cubic or linear Bézier curve segments  C(t) = {c_u (t), c_v (t)}  , comprising the outline of the text symbols. Once the layout is constructed on the surface, a shading process is applied to the text, affecting the width of the symbols as well as their color, according to some shader function. The shader function depends on the surface orientation and the view direction as well as the color and the direction or position of the light source.     

Skeleton-enhanced line drawings for 3D models

We present a novel line drawing approach for 3D models by introducing their skeleton information into the rendering process. Based on the silhouettes of the input 3D models, we first extract feature lines in geometric regions by utilizing their curvature, torsion and view-dependent information. Then, the skeletons of the models are extracted by our newly developed skeleton extraction algorithm. After that, we draw the skeleton-guided lines from non-geometric regions through the skeleton information. These lines are combined with the feature lines to render the final line drawing result using the line optimization. Experimental results show that our algorithm can render line drawings more effectively with enhanced skeletons. The resulting artistic effects can capture the local geometries as well as the global skeletons of the input 3D models.     

Pencil-like sketch rendering of 3D scenes using trajectory planning and dynamic tracking

Objective: We present a new non-photorealistic rendering method to render 3D scenes in the form of pencil-like sketches.Methods: This work is based on the observation that the dynamic feedback mechanism involving the human visual system and the motor control of the hand collectively generates the visual characteristics unique to hand-drawn sketches. At the heart of our approach is a trajectory planning and tracking algorithm that generate the sketch in multiple layers using a dynamic pen model. On each layer, a set of target strokes are generated from the silhouette lines, edges, and shaded regions which serve as the target trajectory for a closed-loop dynamic pen model. The pen model then produces the rendered sketch, whose characteristics can be adjusted with a set of trajectory and tracking parameters. This process continues in several layers until the tonal difference between the sketch and the original 3D render is minimized.Results: We demonstrate our approach with examples that are created by controlling the parameters of our sketch rendering algorithms.Conclusion: The examples not only show typical sketching artifacts that are common to human-drawn sketches but also demonstrate that it is capable of producing multiple sketching styles.     

基于图像的铅笔画模拟绘制技术综述

铅笔画运用画笔在平面上表现出万物的形态、结构、色调、空间、位置、明暗,是造型艺术的基础,是科学、哲学、美学的世界。近年,随着计算机技术及软件技术的进步,铅笔画逐步走上了数字领域。从非真实感铅笔画绘制技术的研究现状出发,根据不同的分类方法分析目前铅笔画模拟绘制技术的优缺点,并对未来的研究方向进行展望。     

Non-photorealistic, depth-based image editing

Recent works in image editing are opening up new possibilities to manipulate and enhance input images. Within this context, we leverage well-known characteristics of human perception along with a simple depth approximation algorithm to generate non-photorealistic renditions that would be difficult to achieve with existing methods. Once a perceptually plausible depth map is obtained from the input image, we show how simple algorithms yield powerful new depictions of such an image. Additionally, we show how artistic manipulation of depth maps can be used to create novel non-photorealistic versions, for which we provide the user with an intuitive interface. Our real-time implementation on graphics hardware allows the user to efficiently explore artistic possibilities for each image. We show results produced with six different styles proving the versatility of our approach, and validate our assumptions and simplifications by means of a user study.     

基于颜色层次矩阵的卡通着色技术

传统的卡通着色技术是基于纹理技术,通过表面属性与光线矢量的关系来确定表面像素色彩.从感知心理学非真实感绘制模型和卡通渲染过程入手,在对传统的卡通着色技术研究分析的基础上,提出了基于颜色层次矩阵的卡通着色技术.不依赖于纹理,而是通过操作颜色层次矩阵进行渲染,其优点是能够实现多层次卡通渲染并在不同的约束条件下,能够灵活快速地实现多种效果.通过与传统方法的比较,结果表明算法具有较高的有效性和灵活性,为计算机非真实感绘制继续进行艺术加工奠定了基础.     

基于三维模型的风格化线条渲染方法

3D模型风格化线条绘制[1]中的一个最大问题是可见性的计算,当前在以复杂的模型计算线条可见性的算法中,不是交互式渲染速度太慢就是渲染后的动画不连贯,由此提出一种在GPU下快速、高质量地计算线条可见性的算法,其利用先进的可编程图形流水线技术,可以支持线条可见性和广泛的风格化选项.实验结果表明,该算法运算速度能够满足交互系统的实时性需求.     

应用遗传算法仿真墨扩散轮廓

墨扩散效果的模拟是水墨画仿真的重要工作之一,在分析绘画材料特性和扩散形成机制的基础上,提出一个全新的基于遗传算法的墨扩散仿真模型系统.首先将笔迹和纸张离散化为笔元和纸元;其次借用遗传算法基本概念和原理,对给定的输入笔迹进行轮廓提取作为初始种群,通过种群个体间的选择、重组和变异等遗传活动模拟笔元的扩散过程;最后为了更好地模拟墨扩散方向,使用Ashikhmin算法合成各种宣纸的自然纹理,增强了真实感.实验结果表明,方法可以生成丰富的扩散效果,并且接近真实水墨画.     

图像和视频油画风格化研究

图像和视频的油画风格化是计算机图形学中非真实感绘制的热点问题之一,在动漫、娱乐等领域有着较广泛的应用。回顾了图像和视频油画风格化绘制的发展过程,分类介绍了各种方法的特点,并比较了不同方法的优缺点。在此基础上,讨论了图像和视频油画风格化绘制存在的难点和可能的研究方向。     

Observational Models of Graphite Pencil Materials

This paper presents models for graphite pencil, drawing paper, blenders, and kneaded eraser that produce realistic looking pencil marks, textures, and tones. Our models are based on an observation of how lead pencils interact with drawing paper, and on the absorptive and dispersive properties of blenders and erasers interacting with lead material deposited over drawing paper. The models consider parameters such as the particle composition of the lead, the texture of the paper, the position and shape of the pencil materials, and the pressure applied to them. We demonstrate the capabilities of our approach with a variety of images and compare them to digitized pencil drawings. We also present image-based rendering results implementing traditional graphite pencil tone rendering methods.