Bidirectional importance sampling for direct illumination
Bidirectional importance sampling for direct illumination
复制标题
直接照明的双向重要性采样
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
W. Heidrich
中科院分区：
文献类型：
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作者：
David Burke;A. Ghosh;W. Heidrich
基于图像的照明表示可以捕获难以以其他形式表示的复杂的现实世界照明。当前基于图像的照明的重要性采样策略在照明和表面BRDF都包含重要高频细节的情况下存在困难-例如，当镜面反射表面被包含小光源的环境贴图照亮时。
我们引入了双向重要性采样的概念，其中样本从表面反射率和光源能量的乘积分布中提取。虽然这种方法使样本选择过程更加昂贵，但我们大大减少了获得良好图像质量所需的可见性测试的数量。因此，我们在相同的计算时间内实现了比以前的采样策略显着的质量改进。
Image-based representations for illumination can capture complex real-world lighting that is difficult to represent in other forms. Current importance sampling strategies for image-based illumination have difficulties in cases where both the illumination and the surface BRDF contain important high-frequency detail – for example, when a specular surface is illuminated by an environment map containing small light sources.
We introduce the notion of bidirectional importance sampling, in which samples are drawn from the product distribution of both the surface reflectance and the light source energy. While this approach makes the sample selection process more expensive, we drastically reduce the number of visibility tests required to obtain good image quality. As a consequence, we achieve significant quality improvements over previous sampling strategies for the same compute time.