自然景物中大气退化模型的研究

从大气中水汽对光照的影响入手，探讨了自然景物图像的退化机制，通过以典型天气情况的观察，总结并推导了基于输运理论的大气光线变化的亮度、饱和度和色度变化的公式，采用该模型对三维地形立体显示进行退化效果表现，其处理结果令人满意。     

利用带约束的图案变形算法生成笔划效果

提出一种利用带约束规则的变形图案生成各种笔划效果的方法,将笔划定义成一个图案模板（称为笔划模板）,并运行基于路径的笔划模板变形算法来产生笔划。引入了三种变形约束规则;位置约束、形状约束和重复性约束。通过这些约束规则,可以控制笔划的变形效果,达到“智能变形”的目的。作为一种非真实感图形绘制技术,文中方法可以用于艺术创作、印染以及陶瓷花纸等工业的图案设计领域。     

植物叶片表面质感建模与真实感绘制研究进展

植物表观的真实感建模是计算机图形学领域的重要研究内容,叶子作为植物最重要的器官,尤其受到广泛的关注。近年来,随着计算机硬件技术和图形算法的快速发展以及对植物叶子生理机理研究的不断深入,植物叶片表观质感建模和真实感绘制的研究取得了很多成果。植物叶片表面光学特性的采集与建模技术是其中的研究热点和难点。从植物叶片真实感质感模型的定义出发,介绍了近年来国内外在植物叶片表面质感建模和真实感绘制方面取得的最新研究进展,并给出详细的分析和总结。最后对该领域研究存在的问题和未来发展方向提出了一些看法。     

动态3D虚拟场景并行化光线跟踪加速结构设计

为提高光线与虚拟场景几何面片求交的计算效率,提出一种基于混合模式的空间加速结构。该方法改进传统的层次包围盒,把细分层次包围盒与空间均匀网格划分相结合,实现了可并行的混合空间加速设计。此外,把帧间可重用的数据抽取至数据缓存,建立多几何群组的加速结构共享,实现了光线跟踪算法的并行优化。实验证明,该混合加速结构能有效加快光线跟踪的光线场景求交判断速度,快速实现光线跟踪并行化计算。     

Stereo‐Consistent Contours in Object Space

Notebook scribbles, art or technical illustrations—line drawings are a simplistic method to visually communicate information. Automated line drawings often originate from virtual 3D models, but one cannot trivially experience their three‐dimensionality. This paper introduces a novel concept to produce stereo‐consistent line drawings of virtual 3D objects. Some contour lines do not only depend on an objects geometry, but also on the position of the observer. To accomplish consistency between multiple view positions, our approach exploits geometrical characteristics of 3D surfaces in object space. Established techniques for stereo‐consistent line drawings operate on rendered pixel images. In contrast, our pipeline operates in object space using vector geometry, which yields many advantages: The position of the final viewpoint(s) is flexible within a certain window even after the contour generation, e.g. a stereoscopic image pair is only one possible application. Such windows can be concatenated to simulate contours observed from an arbitrary camera path. Various types of popular contour generators can be handled equivalently, occlusions are natively supported and stylization based on geometry characteristics is also easily possible.     

Synthesizing Ornamental Typefaces

We present a method for creating ornamental typeface images. Ornamental typefaces are a composite artwork made from the assemblage of images that carry similar semantics to words. These appealing word‐art works often attract the attention of more people and convey more meaningful information than general typefaces. However, traditional ornamental typefaces are usually created by skilled artists, which involves tedious manual processes, especially when searching for appropriate materials and assembling them. Hence, we aim to provide an easy way to create ornamental typefaces for novices. How to combine users' design intentions with image semantic and shape information to obtain readable and appealing ornamental typefaces is the key challenge to generate ornamental typefaces. To address this problem, we first provide a scribble‐based interface for users to segment the input typeface into strokes according to their design concepts. To ensure the consistency of the image semantics and stroke shape, we then define a semantic‐shape similarity metric to select a set of suitable images. Finally, to beautify the typeface structure, an optional optimal strategy is investigated. Experimental results and user studies show that the proposed algorithm effectively generates attractive and readable ornamental typefaces.     

Improving content visibility for high‐ambient‐illumination viewable display and energy‐saving display

Abstract— Nowadays, low‐contrast viewing of LC displays (LCDs) occurs very often, which includes the viewing of mobile LCDs at high ambient illumination and the viewing of LCDs at low‐power mode. These cases result in low‐content visibility and low contrast, leading to an unpleasant viewing experience. In this paper, a technique to improve the perceived contrast and visibility of images at low‐contrast viewing conditions is proposed. The proposed approach enhances image brightness with content and ambient adaptive image brightening and highlights visual parts and boundaries with non‐photorealistic rendering. The proposed technique enables longer battery life for mobile LC devices and makes mobile LC devices viewable at high ambient illumination. It also enables TVs with extreme low‐power consumption and smart‐grid responsive TVs.     

基于三维参数随机L系统的虚拟植物生成算法

提出了一种基于三维参数随机L系统的虚拟植物生成算法.针对简单L系统生成植物形状单一的缺点,采用曲线论的Frenet标架作为三维基本框架,在对植物产生字符串进行递推迭代的同时,对其规则加入随机概率,使生成的字符串在具有随机性的同时又保留了自相似性.此外,对转角与步长均加入了随机扰动,使生成的植物形态在保持生物性状稳定性的同时又兼具了个体差异性,提高了生成植物的真实感.     

大气效果的绘制技术综述

户外场景的一个重要特征就是大气的存在，大气对户外光照的影响直接关系到户外景物绘制的正确性。因此，大气效果的绘制技术，即表现大气在户外景物中存在的绘制技术，在图形学界被广泛地探讨，成为最具挑战性，也是最具吸收力的图形学研究方向。文中回顾了该技术的发展，从辐射传输理论、 天空和太阳模型、大气模型和绘制方法4个方面介绍现有的图形学技术，并对使用这些技术的图形学应用软件以及技术的发展方向作了简要的介绍。