【作者】 陈一帆；

【导师】 杨旭波； 肖双九；

【作者基本信息】 上海交通大学 ， 软件工程， 2009， 硕士

【摘要】 真实光源的获取及重光照是计算机图形学和计算机视觉的两个重要研究领域。而如何将两者结合起来更是一个热门的研究话题,也是一个技术难点。这些技术的研究被应用到了游戏、影视、自动化工业生产各个领域。本文对真实光源的获取及渲染的算法进行了深入的研究,并提出了新的算法。过去的获取真实光源的算法在获得光源信息后,光源信息一般用于基于模型的渲染中,这样的算法在渲染过程中就失去了真实物体的特殊反射信息;而基于图像的重光照算法又往往用于对虚拟光源或环境光的渲染,无法模拟一些特殊的真实光源的光照效果。本文从基于图像的重光照算法入手,由于要渲染出真实光源的特殊光照性质及纹理,因此必须将光源看作近域光源。在近域光场的前提下,本文提出了一个采集物体基图像、获取光照信息及重光照图像生成的一个完整过程计算法:首先,用投影仪作为基本光源,用摄像机来采集用于近域光重光照的物体基图像,建立入射光线与物体反射点之间的对应关系。建立物体的反射场。然后,通过采集基本光源(投影仪)光照图像及真实光源的光照图像,建立真实光源与基本光源之间的对应关系。从而得到真实光源的入射光场。最后,提出了一个新的算法将基图像和光源对应关系进行合成,从而生成物体在真实光源照射情况下得重光照图像。通过上述流程,本文在基于图象的重光照算基础上,创新的实现了前人没实现的对真实光源的渲染。在设计新算法的同时,设计了一个用于采集物体反射场的仪器,可以通过程序控制,自动的采集及物体图像。从而实现不同光源入射角度、不同视角的重光照算法。更多还原

【Abstract】 The real light source acquisition and relighting technology are two important areas of research in the computer graphics and computer vision. And how to combine the two is a hot research topic. These techniques have been applied to the games, film and television, automation of industrial production. In this paper, the real light source acquisition and rendering algorithm have been studied, and we propose a new algorithm.In the past, the information acquired from real light source was used for model-based rendering. This rendering algorithm lost the reflection information of the objects. And image-based relighting algorithms often be used in relighting virtual light source or ambient light, it cannot simulate the effects of real light source.In this paper, we choose image-based relighting algorithms. Because we want to render the property and texture of the real light source, the light source must be seen as the near-field light source. Based on near-light-field, this paper presents an object basis images acquisition method, a process of real light source acquisition, and a relighting algorithm.First of all, we use projector as a basic light source, use camera to capture the basis images which can used in near-field light source relighting, establish the relationship between the incident light ray and the point of reflection, and acquire the reflectance field of the object.Then, in order to get the information of the real incident light source, we capture the images of basic light source (projector light) and the real light source, and build the relationship between the real light source and the basic light source.Finally, we present a new algorithm of rendering using the basis images and the information of the relationship between the real light source and basic light source. Using this algorithm, we can render the relighting result in the case of new real light source.We also design an instrument to capture the reflectance field of the object, which can be automatically controlled to capture the basis images by computer program. It can be used to relight object under different angle of incident light and different angle of view.更多还原