Efficient methods for ambient lighting

This paper presents a model and algorithms for the reflection of the ambient light. Simplifying the rendering equation we derive an ambient transfer function that expresses the response of the surface and its neighborhood to ambient lighting, taking into account multiple reflection effects. The ambient transfer function is built on the obscurances of the point. If we make assumptions that the material properties are locally homogenous and incorporate a real-time obscurances algorithms, then the proposed ambient transfer can also be evaluated in real-time. Our model is physically based and thus can not only provide better results than empirical ambient occlusion techniques at the same cost, but also reveals where tradeoffs can be found between accuracy and efficiency.