基于传输函数的中尺度涡旋时空连续可视化

本文结合二维流线可视化技术和中尺度涡旋识别技术，提出了3种中尺度涡旋时空连续可视化的方法:基于OW参数的涡旋可视化方法、基于栅格模板的涡旋可视化方法和基于矢量模板的涡旋可视化方法，这3种方法分别基于Okubo-Weiss算法、Faghmous的算法和Liu的算法来进行涡旋识别，同时将流场可视化的结果填充到涡旋内部，以获得更好的可视化效果。在可视化过程中本文引入了传输函数来对涡旋中的流线颜色和透明度进行实时交互，能够在控制界面上通过设置Key值点的颜色和位置来控制速度、涡度和OW参数等信息的显示效果。本文在性能和显示效果方面比较了3种方法的优劣。从性能上来讲，性能由高到低依次为:基于OW参数的涡旋可视化方法、基于栅格模板的涡旋可视化方法和基于矢量模板的涡旋可视化方法。从显示效果上来讲，基于OW参数的涡旋可视化方法在三者中最差，效果中有较多的杂乱的短线，同时涡旋边界较小，局限于涡旋核心区；基于栅格模板的涡旋可视化方法较第一种方法的显示效果有所提升，杂乱的短线较少，涡旋相对完整，但由于数据分辨率不够高的原因，在放大多倍后涡旋边界呈现锯齿状；基于矢量模板的涡旋可视化方法显示效果最好，涡旋完整、饱满。同时，因为首先进行了涡旋边界的重构，将涡旋边界矢量化，涡旋边界更加平滑。相对于传统长时间序列的涡旋可视化的方法而言，这3种方法提供了一个美观、动态和更富信息性的可视化方法，同时由于传输函数的加入，其可以成为科研人员研究涡旋的一个实用的工具。

Time-space continuous visualization of mesoscale vortices based on transfer function

In this paper, three methods for continuous visualization of mesoscale eddies are proposed, which are based on the technique of 2D streamline visualization and technique of mesoscale eddies identification: the method of eddy visualization based on OW parameters, the method of eddy visualization based on grid template and the method of eddy visualization method based on vector template. These three methods are respectively based on Okubo-Weiss algorithm, Faghmous algorithm and Liu''s algorithm for eddy recognition, and the visualization results of the flow field are filled into the eddy to obtain better visualization effect. In the process of visualization, we introduce the transfer function to conduct real-time interaction between the color and transparency of the streamline in the eddy, which can control the display effect of setting the velocity, vorticity, OW parameters and other information by setting the color and position of the Key point on the control interface. In addition, we also compared the advantages and disadvantages of the three methods in terms of performance and display effect. In terms of performance, the performance is from high to low: the method of eddy visualization based on OW parameters, the method of eddy visualization based on grid template and the method of eddy visualization method based on vector template. In terms of display effect, the method of eddy visualization based on OW parameters is the worst among the three, with more chaotic short lines and smaller eddy boundary, which is limited to the core region of the eddy. The method of eddy visualization based on grid template has better display effect than the first method, with fewer messy short lines and relatively complete eddy. However, due to the lack of high resolution of data, the eddy boundary appears jagged after being put up for more than one time. The method of eddy visualization method based on vector template has the best display effect. The eddy is complete and full. At the same time, since the eddy boundary is reconstructed and vectorized, the eddy boundary is smoother. Compared with the traditional method of continuous visualization of eddies with long time series, these three methods provide a beautiful, dynamic and more informative visualization method. At the same time, they can become a practical tool for researchers to study eddies due to the addition of transfer function.