基于非结构化三角网格的海洋流场可视化

针对二维流场可视化均是基于结构化网格流场数据的情况，提出一种基于非结构化三角网格的海洋流场可视化策略：使用流线表达流场，流线可视化的主要挑战是种子点放置问题，即流线的初始点，制定了非结构化三角网格下基于特征引导的种子点放置策略，合理放置流线初始点以利于表达流场特征；设计了基于网格密度的层次聚类算法，引入网格密度属性对流线进行聚类并基于聚类质心进行流线放置，在保留了FVCOM 模式数据的多密度性前提下提高了流线可视化效果。实验表明，该方法可以有效地保留流场特征，并且借助 FVCOM 模式的边界拟合性能在海湾、河道等地区取得良好的可视化效果；在此基础上，基于 Cesium引擎开发了基于流线聚类数据的动态流场可视化应用，其是 FVCOM 模式数据首次应用于动态粒子流场的一次尝试，并且具有较好的可视化效果。

Visualization of ocean flow field based on unstructured triangular mesh

The existing two-dimensional flow field visualizations are all based on structured grid flow field data. This paper proposed a strategy of ocean flow field visualization based on unstructured triangular grid, in which the flow field is expressed by streamline. The main challenge faced by streamline visualization lies in the placement of seed point, namely the initial point of streamline. To meet this challenge, a feature-guided seed point placement strategy was designed based on unstructured triangular grid. Thus, streamline initial points can be placed reasonably to facilitate the expression of flow field characteristics. A hierarchical clustering algorithm based on grid density was also designed. The grid density attribute was introduced to cluster the streamline, which was placed based on the centroid of the cluster. The visualization effect of streamline was enhanced on the premise of preserving the multi-density of FVCOM schema data. The experimental results show that the above methods can effectively retain the characteristics of the flow field, and achieve a good visualization effect for such areas as bay and riverway using the boundary fitting of FVCOM model. On this basis, taking advantage of Cesium engine, a dynamic flow field visualization application was developed based on streamline clustering data. This marks the first attempt to apply FVCOM mode data to dynamic particle flow field, and can produce a good visualization effect.