非真实感中艺术风格模拟技术的研究

【作者】 赵彬如；

【导师】 陈雷霆；

【作者基本信息】 电子科技大学 ， 计算机应用技术， 2009， 硕士

【摘要】 非真实感绘制是在传统的计算机图形学基础上发展起来的,既是基于真实感绘制技术的,非真实感绘制也可以被看成为一种特殊的真实感绘制技术,对于手绘图的真实模拟。在近30年内,已经迅速的发展成为计算机图形学中一个独立的分支,成为该领域的研究热点之一,衍生出一组常用于进行非真实绘制的技术方法,例如轮廓线检测和绘制、独特的光照和纹理技术。同真实感绘制技术一样,其渲染方法也经历了从单纯依赖CPU到使用GPGPU分担CPU计算所产生的质的飞跃。当前,非真实感绘制涉及的范围已经非常广泛,特别是游戏制作中。如何在图形引擎中实现无需用户干预的非真实感绘制,成为本文将要解决的问题。目前在各种图形引擎中,特殊效果渲染需要单独编写程序实现。本文的研究目的是将非真实感绘制模块作为工具集通用引擎中特效渲染模块的子模块之一,以插件形式接入引擎主模块。本文利用现代硬件加速技术,提出了一种在图像空间完全使用GPU编程实现的轮廓线提取和绘制算法,并基于Phong光照模型的改进设计了一种适合于NPR绘制的改进光照模型。并将其应用在本文中的两种非真实感风格模拟实现当中。本文实现两种艺术风格的模拟,实现了卡通风格化和钢笔风格化的非真实感绘制。作者通过研究当前非真实感绘制领域多种渲染效果的实现手法,借鉴了其中效果好并且效率高的部分,改进了当前已有的渲染流程中不足的部分。对于卡通风格通过多重渲染,实现了输入三维模型,经历环境光渲染,轮廓线查找、光照模型渲染、卡通着色,背面阴影和投射阴影绘制等多个步骤得到的带阴影的卡通渲染效果,最终得到卡通风格图像的非真实感绘制流水线。本文中的钢笔画风格借助NPR技术中基于图像空间的生成方法,利用各种不同大小及形状的笔划进行三维物体的钢笔画效果自动生成。并结合融合了Slicing技术、MMI技术、层次图像缓存技术和基本布告板技术等大场景实时加速绘制技术的多层次绘制方法,提出植物多层次钢笔风格化绘制技术。本文的实现过程无需用户干预,采用了基于可编程图形硬件的方法,充分利用了可编程图形硬件的计算能力,速度较快,渲染效果较好,可以较好的运用于引擎场景编辑当中,为引擎的特效模块提供了一种全新的特效模式。更多还原

【Abstract】 NPR has absorbed lots of research achievements in realistic rendering. Before that, research of NPR was based on image and most of algorithm was implemented on CPU. Today, the graphics rendering pipeline has been widely used in research and implementation of NPR. For application, NPR technique can cover lots of fields. Especially in game design, it has found more and more extensive applications. How to realize a kind of NPR rending in our engines, is becoming the most important problem of this research.Nowadays in game engines, special effect rending is required to realize by programming solely. The research target of this article is to regard NPR module as a sub-module of special effect rending in our engines and switch in engine main module in plug-in form.The thesis bases on the hardware-accelerate technique,proposes one technique in silhouette detection and rendering based on image space with GPU shader programming, and designs a new illumination model by improving on the Phong illumination model.We use the two techniques in the two artistic rendering realizations of this thesis. The thesis realizes two kind of NPR similar with cartoon and pen-and-ink. The writer researches present realization of multi-rending effects of NPR, borrows the parts with good effect and high efficiency of it to improve the present insufficient parts in rending procedures. For cartoon rendering in this thesis, presents NPR pipelines similar with cartoon pictures by inputting 3-dimension modules, silhouette detecting, outline the profiles and edges of objects in back, illumination model rendering, uniformly color the surface inside the outlines and color uniformly color the surface inside the outlines. For our pen-and-ink rendering in this thesis, studies the automatic generation of pen-and-ink rendering systematically in NPR using strokes with different size and shape, with the method of image-based generation. And combining the pen-and-ink rendering to the multi-layered rendering into which the slicing, MMI(multi mesh imposter), hierarchical image caching and billboard technique are merged. The multi-layered vegetation rendering with the pen-and-ink style is proposed for accelerated drawing of complex environments, ie. forest scene.The presenting procedure does not need the users’intervene. It uses the method based on programmable graphics hardware, utilizes the counting ability of programmable graphics hardware. Since the speed is fast, it could be used in game engines well and provide a brand-new effect to effect module of game engines.更多还原