In this paper, we present a novel method for the direct volume rendering of large smoothed‐particle hydrodynamics (SPH) simulation data without transforming the unstructured data to an intermediate representation. By directly visualizing the unstructured particle data, we avoid long preprocessing times and large storage requirements. This enables the visualization of large, time‐dependent, and multivariate data both as a post‐process and in situ. To address the computational complexity, we introduce stochastic volume rendering that considers only a subset of particles at each step during ray marching. The sample probabilities for selecting this subset at each step are thereby determined both in a view‐dependent manner and based on the spatial complexity of the data. Our stochastic volume rendering enables us to scale continuously from a fast, interactive preview to a more accurate volume rendering at higher cost. Lastly, we discuss the visualization of free‐surface and multi‐phase flows by including a multi‐material model with volumetric and surface shading into the stochastic volume rendering.

中文翻译：

---

多相 SPH 数据的随机体积渲染

在本文中，我们提出了一种新方法，用于大平滑粒子流体动力学 (SPH) 模拟数据的直接体积渲染，而无需将非结构化数据转换为中间表示。通过直接可视化非结构化粒子数据，我们避免了长时间的预处理和大的存储需求。这使得大型、时间相关和多变量数据的可视化成为后处理和原位的可视化。为了解决计算复杂性，我们引入了随机体积渲染，它在光线行进期间的每一步只考虑粒子的一个子集。在每个步骤中选择这个子集的样本概率由此以视图相关的方式和基于数据的空间复杂性来确定。我们的随机体积渲染使我们能够从快速、交互式预览以更高的成本获得更准确的体积渲染。最后，我们通过将具有体积和表面阴影的多材料模型包含到随机体积渲染中来讨论自由表面和多相流的可视化。