A Full-Wave Reference Simulator for Computing Surface Reflectance
A Full-Wave Reference Simulator for Computing Surface Reflectance
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DOI：
10.1145/3592414
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发表时间：
2023-07
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通讯作者：
Yunchen Yu;Mengqi Xia;B. Walter;E. Michielssen;Steve Marschner
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作者：
Yunchen Yu;Mengqi Xia;B. Walter;E. Michielssen;Steve Marschner
计算粗糙表面的光反射是计算机图形学中的一个重要课题。基于几何光学开发的反射模型不能捕捉到诸如衍射和干涉等波的影响，而现有的基于物理光学近似的模型在许多情况下给出错误的预测(例如，当不能忽略来自表面的多次散射时)。我们提出了一个可扩展的三维全波模拟器，用于计算表面散射问题的参考解，该模拟器可以用于评估和指导绘制近似模型的开发。我们研究了一些现有的基于波动光学的反射模型的适用范围；我们的结果证实了这些模型适用于低粗糙度表面，但也表明以前的绘制方法不能准确地预测某些类型表面的散射行为。我们的模拟器基于边界元方法(BEM)，使用自适应积分方法(AIM)进行加速，并在现代GPU上实现。我们在高达60×60×10个波长的区域上演示了该模拟器，其中包括高度变化显著的表面样品。此外，我们提出了一种新的系统，通过结合小的模拟来表征更大的区域，从而有效地同时计算大量入射和出射方向的BRDF值。我们的模拟器将作为计算表面散射的开源工具包发布。
Computing light reflection from rough surfaces is an important topic in computer graphics. Reflection models developed based on geometric optics fail to capture wave effects such as diffraction and interference, while existing models based on physical optics approximations give erroneous predictions under many circumstances (e.g. when multiple scattering from the surface cannot be ignored). We present a scalable 3D full-wave simulator for computing reference solutions to surface scattering problems, which can be used to evaluate and guide the development of approximate models for rendering. We investigate the range of validity for some existing wave optics based reflection models; our results confirm these models for low-roughness surfaces but also show that prior rendering methods do not accurately predict the scattering behavior of some types of surfaces. Our simulator is based on the boundary element method (BEM) and accelerated using the adaptive integral method (AIM), and is implemented to execute on modern GPUs. We demonstrate the simulator on domains up to 60 × 60 × 10 wavelengths, involving surface samples with significant height variations. Furthermore, we propose a new system for efficiently computing BRDF values for large numbers of incident and outgoing directions at once, by combining small simulations to characterize larger areas. Our simulator will be released as an open-source toolkit for computing surface scattering.