Abstract In the in situ visualization of large-scale simulation, if using the traditional sort-last parallel rendering method, the performance cannot be fully improved due to the heavy communication cost in the final stage: compositing of images. In order to resolve this problem, in this paper, we proposed a composition-free parallel volume rendering method. This is achieved by our proposed hybrid parallelization based on the image space partition and octree-based data space partition. Firstly, in the data distribution stage, an octree structure decoupled from volume representation was proposed, which only stored the indicts of sub-blocks, the adjacent sub-blocks, and the space coordinate information of its bounding box. Before rendering, to avoid the compositing stage, a ray-data intersection list was created for each pixel, which sorted by visibility order and identified NON-EMPTY sub-blocks along the ray. Then in the rendering stage, to improve the efficiency of rendering, a ray-data intersection lists-based rendering method was proposed. Finally, we only need to align the partial images to form the final output image. No compositing process is necessary in our parallel volume rendering method. In order to demonstrate the efficiency of our approach, two existing volume rendering methods have been carried out to compare with our composition-free method. Graphic abstract

中文翻译：

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一种无需合成的并行体绘制方法

摘要 在大规模仿真的原位可视化中，如果采用传统的sort-last并行渲染方法，由于最后阶段的通信开销大：图像合成，性能无法得到充分提升。为了解决这个问题，在本文中，我们提出了一种无合成的并行体绘制方法。这是通过我们提出的基于图像空间分区和基于八叉树的数据空间分区的混合并行化实现的。首先，在数据分发阶段，提出了一种与体积表示解耦的八叉树结构，它只存储子块的指示、相邻子块及其边界框的空间坐标信息。在渲染之前，为了避免合成阶段，为每个像素创建了一个光线数据交叉列表，它按可见性顺序排序并沿射线识别非空子块。然后在渲染阶段，为了提高渲染效率，提出了一种基于光线数据交叉列表的渲染方法。最后，我们只需要对齐部分图像就可以形成最终的输出图像。在我们的并行体渲染方法中不需要合成过程。为了证明我们方法的效率，已经进行了两种现有的体绘制方法，以与我们的无组合方法进行比较。图形摘要 在我们的并行体渲染方法中不需要合成过程。为了证明我们方法的效率，已经进行了两种现有的体绘制方法，以与我们的无组合方法进行比较。图形摘要 在我们的并行体渲染方法中不需要合成过程。为了证明我们方法的效率，已经进行了两种现有的体绘制方法，以与我们的无组合方法进行比较。图形摘要