Fluorescent materials can shift energy between wavelengths, thereby creating bright and saturated colors both in natural and artificial materials. However, rendering fluorescence for continuous wavelengths or combined with wavelength dependent path configurations so far has only been feasible using spectral unidirectional methods. We present a regularization‐based approach for supporting fluorescence in a spectral bidirectional path tracer. Our algorithm samples camera and light sub‐paths with independent wavelengths, and when connecting them mollifies the BSDF at one of the connecting vertices such that it reradiates light across multiple wavelengths. We discuss arising issues such as color bias in early iterations, consistency of the method and MIS weights in the presence of spectral mollification. We demonstrate our method in scenes combining fluorescence and transport phenomena that are difficult to render with unidirectional or spectrally discrete methods.

中文翻译：

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双向荧光的光谱摩尔化

荧光材料可以在波长之间转移能量，从而在天然和人造材料中产生明亮和饱和的颜色。然而，迄今为止，为连续波长呈现荧光或与波长相关的路径配置相结合，只有使用光谱单向方法才可行。我们提出了一种基于正则化的方法来支持光谱双向路径追踪器中的荧光。我们的算法对具有独立波长的相机和光子路径进行采样，并在连接它们时在连接顶点之一缓和 BSDF，使其重新辐射多个波长的光。我们讨论了出现的问题，例如早期迭代中的颜色偏差、方法的一致性和存在光谱软化的 MIS 权重。