Computing Light Transport Gradients using the Adjoint Method
Computing Light Transport Gradients using the Adjoint Method
复制标题
使用伴随方法计算光传输梯度
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
J. Stam
中科院分区：
文献类型：
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作者：
J. Stam
本文从连续伴随理论出发，提出了一个计算光输运理论所支配的量的梯度的新方程。与在代码级别工作的离散梯度不同，我们首先阐述连续理论，然后对其进行离散化。这篇文章的关键观点是，在输运理论中计算梯度类似于计算重要性，一个伴随着辐射度的量，满足伴随方程。重要性告诉我们在哪里寻找重要的光。这是本文的主要见解之一。事实上，这段数学之旅始于一种异想天开的想法，即这些伴随词可能是相关的。因此，计算梯度并不比计算重要性域更复杂。这一见解和随后的论文有望对这一复杂问题提供一些启示，并简化现有路径跟踪器中梯度计算的实现。
This paper proposes a new equation from continuous adjoint theory to compute the gradient of quantities governed by the Transport Theory of light. Unlike discrete gradients ala autograd, which work at the code level, we first formulate the continuous theory and then discretize it. The key insight of this paper is that computing gradients in Transport Theory is akin to computing the importance, a quantity adjoint to radiance that satisfies an adjoint equation. Importance tells us where to look for light that matters. This is one of the key insights of this paper. In fact, this mathematical journey started from a whimsical thought that these adjoints might be related. Computing gradients is therefore no more complicated than computing the importance field. This insight and the following paper hopefully will shed some light on this complicated problem and ease the implementations of gradient computations in existing path tracers.