Volume rendering methods have been extensively studied in recent years due to their effectiveness and expressiveness for unstructured grid data visualization. Although existing volume rendering methods have demonstrated great success, we observe that these methods have extensive interpolation and integral operations, which may adversely affect their efficiency and further prevent them being applied in interactive visualization. To boost efficiency and achieve interactive rendering rates, we propose a novel multi-threaded parallel projection tetrahedral algorithm based on multi-core architecture. By analyzing the parallelism of volume rendering methods, we find that the visibility sorting and classification/decomposition of projection polygons are the most time-consuming parts. To reduce the execution time of these two parts, we design corresponding parallel methods. In this manner, our method can dramatically improve efficiency and further enable user interactions for progressive unstructured grid analysis. The visibility sorting part includes partial sorting and global sorting: In partial sorting, we partition disordered tetrahedral depth array and obtain several loosely coupled subarrays, and in global sorting, we sort each subarray with multi-threads technique. In the classification/decomposition of projection polygons part, we normalize tetrahedral projection to ensure arbitrary tetrahedral produces the same number of triangles, and then store the produced vertex data into vertex array with offset computation that ensures correct order for the multi-threads runtime. The experimental results show that the proposed multi-threaded projection tetrahedral algorithm can achieve a speedup of 3.4X on a 20 cores CPU and outperforms the fastest VTK implementation at a speedup of 2.5X, which verifies the efficiency of our algorithm.

中文翻译：

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非结构化体绘制的多线程平行投影四面体算法

近年来，体绘制方法因其对非结构化网格数据可视化的有效性和表现力而得到广泛研究。尽管现有的体绘制方法已经取得了巨大的成功，但我们观察到这些方法具有广泛的插值和积分运算，这可能会对它们的效率产生不利影响，并进一步阻碍它们在交互式可视化中的应用。为了提高效率并实现交互式渲染速率，我们提出了一种基于多核架构的新型多线程并行投影四面体算法。通过分析体绘制方法的并行性，我们发现投影多边形的可见性排序和分类/分解是最耗时的部分。为了减少这两部分的执行时间，我们设计了相应的并行方法。通过这种方式，我们的方法可以显着提高效率并进一步实现用户交互以进行渐进式非结构化网格分析。可见性排序部分包括部分排序和全局排序：在部分排序中，我们对无序四面体深度数组进行划分，得到几个松耦合的子数组，在全局排序中，我们使用多线程技术对每个子数组进行排序。在投影多边形的分类/分解部分，我们将四面体投影归一化以确保任意四面体产生相同数量的三角形，然后将产生的顶点数据存储到具有偏移计算的顶点数组中，以确保多线程运行时的正确顺序。