陳炳宇Chen, Bing-Yu臺灣大學:資訊工程學研究所陳心怡Chen, Hsin-YiHsin-YiChen2010-05-172018-07-052010-05-172018-07-052009U0001-2907200920142400http://ntur.lib.ntu.edu.tw//handle/246246/183396室外場景不同的光影呈現, 往往帶給觀賞的人不一樣的視覺感受.是在很多狀況下,我們對場景所拍攝的照片不一定能捕捉到我們想要光線.這篇論文中,我們提供了一套轉換場景光線的系統,不需要真實的物理射模型或事先獲得場景的3D資訊,而得以對場景中的光線進行轉換.們利用拍攝不同光源方向,但是同樣視角的室外場景影片,利用非負矩分解, 還原出場景的法向量,可能的物理反射模型以及光源的方向和度. 利用求得的幾何參數和另外一組場景的光源方向和強度, 我們可將不同光源的特性轉換到我們想要改變光源的場景上, 合成擬真的繪.Lighting makes a significant perceptual impact on visual perception,ut our photo are sometimes captured during rather bother lighting condition.e propose a method to transfer lights from one outdoor scene tonother by using sequences of time-varying videos taken from both scenes.ur algorithm first detect shadow area for each image. We consider pixels inhadow as unreliable data, then using an iterative photometric stereo frameworkith non-negative matrix factorization method to compute geometryerm and lighting term of the scene. The factorization result allows users toasily relight the scene by transfer lighting from user specified lighting modelo the target image. We demonstrate via several examples that our methodenerates good results and keep color consistency口試委員審定書謝文摘要bstract Introduction 1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Problem statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Related Work 5.1 Time-lapse sequence analysis . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Photometric stereo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Relighting of outdoor scene . . . . . . . . . . . . . . . . . . . . . . . . . 7 Overview 9 Video Processing 13.1 Sky Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Frame extraction and Alignment . . . . . . . . . . . . . . . . . . . . . . 14.3 Lighting Clustering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Model Formulation 17.1 Lambertian Surface Model . . . . . . . . . . . . . . . . . . . . . . . . . 17.2 Orientation From Colour . . . . . . . . . . . . . . . . . . . . . . . . . . 18.2.1 Photometric Stereo Using Factorization . . . . . . . . . . . . . . 18.3 Matrix Factorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.3.1 Non-negative Matrix Factorization . . . . . . . . . . . . . . . . . 23.4 Problem Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Algorithm 25.1 Shadow Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.2 First Factorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2.1 Surface Normal and Light Direction Estimation . . . . . . . . . . 32.3 Second Factorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.3.1 Surface Albedo Estimation . . . . . . . . . . . . . . . . . . . . . 34.3.2 Light Intensity Estimation and Normalization . . . . . . . . . . . 34.4 Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.4.1 Sky Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . 36.4.2 Relighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Result 37 Conclusion and Future work 45.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.2 Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45ibliography 47application/pdf2880836 bytesapplication/pdfen-US影像式描繪逆向問題計算攝影學image-based rendering,inverse problemcomputational photographythesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/183396/1/ntu-98-R96922129-1.pdf