Convincing simulation of diffraction around obstacles is critical in modeling sound propagation in virtual environments. Due to the computational complexity of large-scale wavefield simulations, ray-based models of diffraction are used in real-time interactive multimedia applications. Among popular diffraction models, the Biot-Tolstoy-Medwin (BTM) edge diffraction model is the most accurate, but it suffers from high computational complexity and hence is difficult to apply in real time. This paper introduces an alternative ray-based approach to approximating diffraction, called Volumetric Diffraction and Transmission (VDaT). VDaT is a volumetric diffraction model, meaning it performs spatial sampling of paths along which sound can traverse the scene around obstacles. VDaT uses the spatial sampling results to estimate the BTM edge-diffraction amplitude response and path length, with a much lower computational cost than computing BTM directly. On average, VDaT matches BTM results within 1–3 dB over a wide range of size scales and frequencies in basic cases, and VDaT can handle small objects and gaps better than comparable state-of-the-art real-time diffraction implementations. A GPU-parallelized implementation of VDaT is shown to be capable of simulating diffraction on thousands of direct and specular reflection path segments in small-to-medium-size scenes, within strict real-time constraints and without any precomputed scene information.

中文翻译：

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用于实时声音传播模拟的近似衍射模型

令人信服的围绕障碍物的衍射模拟对于模拟虚拟环境中的声音传播至关重要。由于大规模波场模拟的计算复杂性，在实时交互式多媒体应用中使用了基于射线的衍射模型。在流行的衍射模型中，Biot-Tolstoy-Medwin（BTM）边缘衍射模型是最准确的，但是它具有很高的计算复杂度，因此难以实时应用。本文介绍了另一种基于射线的近似衍射方法，称为体积衍射和透射（VDaT）。VDaT是一个体积衍射模型，意味着它对路径进行空间采样，声音可以沿着这些路径遍历障碍物周围的场景。VDaT使用空间采样结果来估计BTM边缘衍射幅度响应和路径长度，其计算成本比直接计算BTM低得多。在基本情况下，VDaT平均可以在各种尺寸和频率范围内将BTM结果匹配在1-3 dB之内，并且VDaT可以比同类的最新实时衍射实现更好地处理小物体和间隙。VDaT的GPU并行实现被证明能够在严格的实时约束下且没有任何预先计算的场景信息的情况下，模拟中小型场景中数千个直接和镜面反射路径段上的衍射。