ABSTRACT

Many studies have been focused on rendering 2D vector elements on 3D terrain, and a series of algorithms have been proposed. Most of these algorithms struggle to provide a seamless overlay between vector elements and an irregular terrain surface. Despite their importance, the physical characteristics of vector elements are often ignored, which distorts the surface of vector elements. For example, if vector elements that represent roads and rivers are simply overlaid on terrain, the phenomena of uneven surfaces and rivers going uphill may occur because of elevation fluctuation. To correct these deficiencies, terrain should be modified according to the physical characteristics of vectors. We propose a local terrain modification method: First, the elevation of terrain covered by vector elements is recalculated according to vectors’ physical characteristics. Second, the multigrid method is used to realize a smooth transition between the modified terrain and its surrounding area. Finally, by setting different transition ranges and comparing the visualization effects, rules are given for the selection of a suitable range. After modification, the terrain conforms to vectors’ physical characteristics, and the overall relief is undamaged. The proposed method was applied to a CPU–GPU parallel heterogeneous model and demonstrated a high level of performance.

摘要

许多研究集中于在3D地形上渲染2D矢量元素，并且提出了一系列算法。这些算法大多数都难以在矢量元素和不规则地形表面之间提供无缝覆盖。尽管它们很重要，但矢量元素的物理特性经常被忽略，这扭曲了矢量元素的表面。例如，如果将代表道路和河流的矢量元素简单地覆盖在地形上，则由于海拔波动，可能会出现不平坦的表面和河流上坡的现象。要纠正这些缺陷，应根据矢量的物理特性修改地形。我们提出了一种本地地形修改方法：首先，根据矢量的物理特征重新计算矢量元素覆盖的地形的高程。其次，使用多网格方法来实现修改后的地形与其周围区域之间的平滑过渡。最后，通过设置不同的过渡范围并比较可视化效果，给出了选择合适范围的规则。修改后，地形符合矢量的物理特征，整体地形没有受到破坏。所提出的方法被应用于CPU-GPU并行异构模型，并展示了高水平的性能。给出了选择合适范围的规则。修改后，地形符合矢量的物理特征，整体地形没有受到破坏。所提出的方法被应用于CPU-GPU并行异构模型，并展示了高水平的性能。给出了选择合适范围的规则。修改后，地形符合矢量的物理特征，整体地形没有受到破坏。所提出的方法被应用于CPU-GPU并行异构模型，并展示了高水平的性能。