臺灣博碩士論文加值系統

在包含數位特效的電影或電腦動畫中，燈光設計一直是個耗時又耗力的過程。燈光設計師需要一套互動式的工具讓他們得以即時預覽結果，但又不希望預覽與最終繪製的結果差異過大。

在這篇論文中，我們提供了一套解決燈光師難題的打光系統。藉由事先運算並儲存的著色快取影像，再加上繪圖硬體的加速，這套系統可以快速產生品質良好的打光預覽圖。我們也使用多層著色快取影像的方式，提供了鏡面反射的效果。

全域照明也是這篇論文的重點。我們提出了一套根基於光能採集點的演算法，並藉由採集點間的能量交換來計算間接照明能量。我們的主要貢獻在於對雙向反射分佈函數進行分解，比起傳統假設材質皆為漫射面的方法，我們的演算法能更有效地模擬似鏡面材質間的能量傳遞。

In computer cinematography and animation, the process of lighting design is time consuming and labor intensive. Lighting artists need an interactive tool which gives fast preview without losing too much quality compared with the final result.

In this thesis, we present a relighting system which solves the problem faced by lighting artists. By caching shading parameters in deep framebuffer and rendering with graphics hardware acceleration, our system gives convincible lighting preview interactively. Our system also captures specular reflections by layered deep framebuffer.

Global illumination for relighting system is also emphasized in this thesis. We proposed a new approach based on transferring indirect illumination from gather samples. Our main contribution is extending the light transport path to glossy inter-reflections by BRDF factorization.

致謝 ⅰ
摘要 ⅲ
Abstract ⅴ
1 Introduction 1
1.1 Motivation 1
1.2 Problem statement 1
1.3 Organization 2

2 Related Work 3
2.1 Relighting engines 3
2.2 Precomputed radiance transfer 3
2.3 Global illumination 4

3 Relighting System 5
3.1 Deep framebuffer 5
3.2 Rendering 5
3.3 Light scalability 7
3.4 Specular reflections 8
3.5 Shadows 8

4 Global Illumination 11
4.1 Basic derivation 11
4.2 Diffuse direct-to-indirect transfer 13
4.3 Glossy direct-to-indirect transfer 15
4.4 BRDF factorization 16
4.5 Limitations 19

5 Experiments and Results 21
5.1 Relignting system 21
5.2 Glossy direct-to-indirect transfer 24

6 Conclusion and Future Work 29

Bibliography 31

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