时变体数据传输函数设计及其在行星际数值模拟结果可视化中的应用  

A Time-varying Volume Data Transfer Function for Interplanetary Numerical Simulation Data

作　　者：祝艳 钟鼎坤 ZHU Yan;ZHONG Dingkun(National Space Science Center,Chinese Academy of Sciences,Beijing 100190;University of Chinese Academy of Sciences,Beijing 100049)

机构地区：[1]中国科学院国家空间科学中心,北京100190 [2]中国科学院大学,北京100049

出　　处：《空间科学学报》2023年第3期423-433,共11页Chinese Journal of Space Science

基　　金：国家自然科学基金项目资助(41874202,42030204)。

摘　　要：为便于太阳风暴行星际传播数值模型结果可视化分析,提出一种针对时变模拟数据体绘制的传输函数设计算法(Transfer Function for Time-varying Volume data,TFTV)。该算法首先基于KNN(K-Nearest Neighbors,KNN)背景差分法提取运动区域;然后,利用频率调谐(Frequency Tuned,FT)显著性算法检测日冕物质抛射(Coronal Mass Ejection,CME),并设计颜色反映射算法查找CME与背景的分界阈值;最后,基于阈值自适应调整传输函数实现各时间步上运动区域中CME的快速三维可视化。实验结果表明,该算法能够适应静态及动态背景下CME的数值模型结果,相对于线性传输函数有效避免了视线方向的遮挡,直观自动地展示了相对动量的变化,示踪行星际空间中CME的演化过程,局部区域的提取降低了数据冗余,借助算法自动分析数据自适应调整传输函数避免了人工调整的低效性。Understanding the interplanetary propagation of solar storms is the foundation of space environmental forecasting and services.The visualization of numerical model simulation data is an important method to analyze the propagation dynamics process and verify the validity of the model.In order to facilitate the visualization analysis of the numerical model simulation data with increasing simulation scale,a Transfer Function for Time-varying Volume data rendering(TFTV)based on the characteristics of time domain and frequency domain is proposed.The algorithm is designed to extract images including motion regions based on the K-Nearest Neighbor(KNN)background subtraction method,and then the three-dimensional subset of the moving region can be extracted according to the mapping relationship between the image and the volume data to achieve the reduction of large-scale grid volume data.Then the Frequency Tuned(FT)salient region detection algorithm is used to detect Coronal Mass Ejection(CME)in motion area images,and according to the CME detection results,a color inverse mapping algorithm is designed to find the boundary threshold between the CME and interplanetary space background.Finally,the transfer function design in volume visualization is adaptively adjusted based on the threshold to realize the fast 3D visualization of CME in the motion region at each time step.The experimental results show that TFTV transfer function algorithm can adapt to the numerical model simulation data in static and dynamic backgrounds.Compared with the linear transfer function,the occlusion of the line in sight direction is effectively avoided,the change of relative momentum is intuitively and automatically displayed,and the evolution process of CME in interplanetary space is traced.The extraction of local regions reduces data redundancy,and the process of adaptively adjusting the transfer function by automatically analyzing the data with the help of algorithms avoids the inefficiency of manual adjustment.

关 键 词：体绘制 传输函数 可视化 数值模拟 

分 类 号：P35[天文地球—空间物理学] TP391.41[天文地球—地球物理学]