Donikian Michael, Walter Bruce, Bala Kavita, Fernandez Sebastian, Greenberg Donald P
53d Test Support Squadron, Tyndall Air Force Base, FL 32403, USA.
IEEE Trans Vis Comput Graph. 2006 May-Jun;12(3):353-64. doi: 10.1109/TVCG.2006.41.
This paper introduces a new multipass algorithm for efficiently computing direct illumination in scenes with many lights and complex occlusion. Images are first divided into 8 x 8 pixel blocks and for each point to be shaded within a block, a probability density function (PDF) is constructed over the lights and sampled to estimate illumination using a small number of shadow rays. Information from these samples is then aggregated at both the pixel and block level and used to optimize the PDFs for the next pass. Over multiple passes the PDFs and pixel estimates are updated until convergence. Using aggregation and feedback progressively improves the sampling and automatically exploits both visibility and spatial coherence. We also use novel extensions for efficient antialiasing. Our adaptive multipass approach computes accurate direct illumination eight times faster than prior approaches in tests on several complex scenes.
本文介绍了一种新的多遍算法，用于在具有多个光源和复杂遮挡的场景中高效计算直接光照。图像首先被划分为8×8像素的块，对于块内每个要着色的点，在光源上构建概率密度函数（PDF），并使用少量阴影光线进行采样以估计光照。然后，这些样本的信息在像素和块级别进行聚合，并用于优化下一遍的PDF。经过多遍，PDF和像素估计会不断更新，直到收敛。使用聚合和反馈可以逐步改进采样，并自动利用可见性和空间连贯性。我们还使用了新颖的扩展来实现高效的抗锯齿。在对几个复杂场景的测试中，我们的自适应多遍方法计算精确直接光照的速度比先前方法快八倍。
