在螢幕空間中做環境遮擋與間接照明

Abstract

即時的全域照明在電腦圖學一直是很重要的研究主題，過去最普遍的方法為環境遮擋(Ambient Occlusion)，之後CryTek在他的遊戲引擎更加以改進提出一個能在螢幕空間(Screen Space)中近似環境遮擋效果的方法。本篇論文提出一個結合螢幕空間的環境遮擋(SSAO)及反射陰影圖(Reflective Shadow Map)在延遲著色中近似全域照明的方法。以螢幕空間的環境遮擋為基礎加入區域直接照明(Local direct illumination)及全域間接照明(Global indirect illumination) ，並在螢幕空間中進行內插以減少GPU的負擔，由於我們主要在螢幕空間上做計算所以不受場景複雜程度的影響。我們經由實作證明本演算法所產生的結果可以顯示於較大且動態的場景，並可達到即時描繪的效能。

Real-Time Global illumination in computer graphics is a very important topic. In the past, a popular approach was ambient occlusion. Then CryTek Company improves this algorithm. They propose an approach to approximate ambient occlusion in the screen space. In this thesis, we introduce a further enhancement to approximate global illumination by combining screen space ambient occlusion and reflective shadow map in a deferred shading context. We include local direct illumination and global indirect illumination by extending screen space ambient occlusion. On the other hand, we reduce GPU overhead by using screen-space interpolation. Since the algorithm works in screen space, it does not depend on the geometric complexity of 3D scenes. We demonstrate the result which can be displayed for large and fully dynamic scenes at real-time frame rates.