Rendering near-field speckle statistics in scattering media
Rendering near-field speckle statistics in scattering media
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DOI：
10.1145/3414685.3417813
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
Chen Bar;Ioannis Gkioulekas;Anat Levin
中科院分区：
文献类型：
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作者：
Chen Bar;Ioannis Gkioulekas;Anat Levin
我们介绍了用于模拟相干近场成像条件下在散射介质中观察到的散斑统计的渲染算法。我们工作的动机是最近在组织成像应用中使用散斑相关的技术的激增：能够以物理上准确和计算高效的方式模拟这些散斑成像技术所使用的图像测量，可以促进这些技术的广泛采用和改进。为此，我们从最近引入的蒙特卡罗算法中获得了灵感，用于绘制远场条件(准直传感器和照明)下的散斑统计数据。我们得出了这些算法的变体，它们更适合组织成像应用所需的近场条件(聚焦传感器和照明)。我们的方法是基于高斯变迹来逼近传感器和照明光圈，以及冯·米塞斯-费雪函数来逼近散射材料的相函数。我们证明，这些近似允许我们推导出模拟近场散斑图案所涉及的聚焦操作的闭合形式的表达式。正如我们在实验中证明的那样，这些近似比以前的技术加速了几个数量级的斑点渲染模拟，但代价是可以忽略不计的偏差。我们通过再现使用波动光学解算器模拟的地面真实散斑统计和文献中提供的真实材料测量来验证我们算法的准确性。最后，我们使用我们的算法来模拟通过组织聚焦的生物医学成像技术。
We introduce rendering algorithms for the simulation of speckle statistics observed in scattering media under coherent near-field imaging conditions. Our work is motivated by the recent proliferation of techniques that use speckle correlations for tissue imaging applications: The ability to simulate the image measurements used by these speckle imaging techniques in a physically-accurate and computationally-efficient way can facilitate the widespread adoption and improvement of these techniques. To this end, we draw inspiration from recently-introduced Monte Carlo algorithms for rendering speckle statistics under far-field conditions (collimated sensor and illumination). We derive variants of these algorithms that are better suited to the near-field conditions (focused sensor and illumination) required by tissue imaging applications. Our approach is based on using Gaussian apodization to approximate the sensor and illumination aperture, as well as von Mises-Fisher functions to approximate the phase function of the scattering material. We show that these approximations allow us to derive closed-form expressions for the focusing operations involved in simulating near-field speckle patterns. As we demonstrate in our experiments, these approximations accelerate speckle rendering simulations by a few orders of magnitude compared to previous techniques, at the cost of negligible bias. We validate the accuracy of our algorithms by reproducing ground truth speckle statistics simulated using wave-optics solvers, and real-material measurements available in the literature. Finally, we use our algorithms to simulate biomedical imaging techniques for focusing through tissue.