Illumination in the Presence of Weak Singularities
Illumination in the Presence of Weak Singularities
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DOI：
10.1007/3-540-31186-6_15
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
T. Kollig;A. Keller
中科院分区：
文献类型：
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作者：
T. Kollig;A. Keller
在许多专业应用中，通过点光源近似照明允许有效的算法，但遭受弱奇异性的问题：除了避免由点光源和要照明的点之间的平方距离的除法引起的数值异常之外，估计器应该是无偏的和有限方差的。我们首先说明，剪切弱奇点到一个合理的值的常见做法产生明显可见的偏见。然后，我们提出了一个新的全局照明算法，是公正的，简单的路径跟踪器，但优雅地避免了弱奇异性的问题。为了证明其性能，该算法已被集成在一个互动的全球照明系统。
Approximating illumination by point light sources, as done in many professional applications, allows for efficient algorithms, but suffers from the problem of the weak singularity: Besides avoiding numerical exceptions caused by the division by the squared distance between the point light source and the point to be illuminated, the estimator should be unbiased and of finite variance. We first illustrate that the common practice of clipping weak singularities to a reasonable value yields clearly visible bias. Then we present a new global illumination algorithm that is unbiased and as simple as a path tracer, but elegantly avoids the problem of the weak singularity. In order to demonstrate its performance, the algorithm has been integrated in an interactive global illumination system.