基于GPU编程的实时卡通渲染研究与实现

【作者】 张涛；

【导师】 朱清新；

【作者基本信息】 电子科技大学 ， 计算机应用技术， 2010， 硕士

【摘要】 卡通渲染(Cel-Rendering或Cartoon Rendering)技术是非真实感渲染技术(Non-Photorealistic Computer Graphics,NPR)的一种,其目的是将输入的场景渲染成卡通风格,其绘制特点是有显著的轮廓边缘和非连续的颜色过渡,与其他效果相比更能让人产生亲切可爱的感觉。卡通渲染技术的主要应用范围是在卡通片、电影及电脑游戏中。世界上已经有很多成熟的利用卡通渲染技术制作的成功的卡通电影和电脑游戏。我国目前在这方面的研究与国外相比还比较落后,还没有很突出的成就。本文首先介绍了卡通渲染技术的发展背景和研究现状,并对研究目标和研究方法做了说明。之后分章节讨论了实时卡通渲染技术涉及的研究领域,包括GPU编程技术、卡通着色、轮廓线检测与绘制。最后对本文的研究工作做了总结并展望了卡通渲染技术的发展方向。GPU编程技术是利用着色器语言对可编程图形硬件进行流程控制,达到充分利用图形硬件资源和实现定制渲染结果的目的。可编程图形流水线是在原图形流水线作了进一步的改进,在顶点处理阶段允许程序设计在使用自己编写的指令控制定点位置和进行光照计算,以及在光栅化阶段实现定制纹理采样及颜色混合。卡通渲染主要包含两个方面:卡通着色和轮廓线绘制。卡通着色是对场景着色得出像素显示颜色的过程。但卡通着色效果不同于真实感的连续光照效果,而是会出现大块的色彩填充和非连续的颜色过渡。本文通过介绍简单光照模型和明暗处理模型在卡通着色技术上的应用,探讨了卡通渲染的着色方法。轮廓线的绘制是卡通渲染技术乃至整个非真实感渲染领域的基础,卡通效果中常用轮廓线来勾勒形状,并对线条加粗以表现模型的重要特征。本文对非真实感渲染领域中使用的轮廓线的定义做了简要介绍,并对目前轮廓线绘制的主要方法做了研究对比,在对现有的成就做了大量的研究和分析后,结合前人优秀思想提出了一种适用于该项目的新的算法并做了性能和效果评估,经过验证了其可行性后,将其应用在了项目中。最后,本文对目前的工作进行了总结,并提出了改进的方向以及将来的工作。更多还原

【Abstract】 Cartoon rendering or cel-rendering is a kind of non-photorealistic rendering technology. We can render the 3D models with cartoon-style effects with it. By computer .Cartoon rendering technology uses the unchanged color and notable contour to bring us a cartoon world, which makes people feel more comfortable and kindly.Cartoon rendering technology has been widely applied to movie making and animations. Overseas cartoon rendering have been applied to the computer and video game. But in China, we are still being behind in the research of Computer Animation&Digital Entertainment field.First, this article introduced the development process and research status of the cartoon rendering technology, then explained the purpose and measure of this article. After that, this article used many chapters to do a detailed study of the key sub-technologies of cartoon rendering, such as shader programming, cartoon shading, contour detection and rendering, and so on.Shader programming is a technology with which we can control the rendering progress by run our own GPU program on the programmable graphics pipeline. By programming the code of vertex shader and pixel shader, we can achieve even go beyond the work of fixed-function module.The programmable graphics pipeline is base on the fixed-function graphics pipeline,adding the programmable transform and lighting modules in the vertex treatment phase, as well as the programmable texture, filtering and hybrid module in the pixel treatment phase.The cartoon rendering technology mainly includes two key sub-technologies, cartoon shading and contour rendering. Cartoon shading is the process of calculating the color of all pixels, and this process is different from traditional realistic shading method. This article researched the entire cartoon shading method by the simple illumination model and several classical shading.Contour rendering is the foundation of cartoon rendering even NPR. The cartoon rendering usually use it to outline the shape of model, and use thick lines to show the important feature. In this article the contours definition and classification of non-photorealistic has been detailed. After that, this paper analyzed all the algorithm of cartoon rendering and contrasts them by programming and tries to get a new suitable algorithm for our project.Finally, we summarize the current work and put forward the direction of improving and the future work.更多还原