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Ambient Occlusion Fields Janne Kontkanen, Samuli Laine to appear in ACM Siggraph 2005 Symposium on Interactive 3D Graphics and Games

Abstract

We present a novel real-time technique for computing inter-object ambient occlusion. For each occluding object, we precompute a field in the space surrounding the object that encodes an approximation of the occlusion caused by the object. This volumetric information is then used at run-time in a fragment program for quickly determining the shadow cast on the receiving objects. According to our results, both the computational and storage requirements are low enough for the technique to be directly applicable to computer games running on the current graphics hardware. http://www.tml.hut.fi/~janne/aofields/

使用的方法是对于每个occluder采用2组cube map来保存每个方向的a,b,c(用来计算这个方向在距离r上的立体角)还有Co和平均方向r。这样计算的时候通过计算得到的立体角和平均方向和法线方向的点乘结果取得于计算好的一张2D Texture获得AO值。