# SINDVis: User-Centered Dynamic Interactive Visualization System for Space Information Networks
## 2 Related Work
### Dynamic Visualization and Visual Analysis  
Network visualization is a branch of information visualization that can be traced back to static graph visualization [7]. With gradual research, people found that topology evolution has become a major feature of networks. Therefore, static network visualization was unable to meet the real needs. Since then, scholars have gradually introduced the concept of time and started to study dynamic visualization.  
Dynamic visualization [8] is a relatively young cross-field. It is mainly used to research the visual view change laws due to the nodes and edge changes of the network over time. Dynamic visualization can make full use of the human visual perception system to display dynamic data graphically. On the  
Figure 4: Composition structure of Ground layer terminals.  
Figure 3: Composition structure of the Near Space layer information system.  
one hand, it can help users to understand the internal structure of network, and on the other hand, it helps to uncover potential value, because dynamic data is constantly updated, and the impacts of the newly generated data on the original visualization are uncontrollable and unpredictable [9]. Therefore, this poses a challenge to the network dynamic visualization. Combined with the visual perception characteristics of the visual view, the design of dynamic visualization should aim to ensure continuity and consistency between frames.  
People take visual analysis as the third paradigm after visualization in scientific computing (VISC) and information visualization, and it involves the inheritance and development of visualization technology. VISC and information visualization are more inclined towards the previous view, and the visual analysis is more inclined towards post-analysis based on the visual view [10]. Visualization technologies have covered many aspects of people's daily lives and work. With the widespread popularization of the Internet and mobile terminals, people can not only enjoy the technology dividends, but also realize that \"one picture speaks one thousand words\", based on the visualization technologies. After decades of development, visualization has gradually developed into a valid area of data analysis. In addition, it has gradually developed from VISC, information visualization to big data visualization, dynamic visualization, and visual analysis as well as other directions and branches.  
Similar to other visualization technologies, there are some basic functional and performance requirements for dynamic visualization and visual analysis techniques. On the one hand, it is necessary to meet the basic aesthetic criteria throughout the visualization process [11]. On the other hand, the user's mental map must always be maintained [12]. Meeting the above functional and performance requirements are the criteria for evaluating the effectiveness of the visualization.  
The literature presents three aspects to realize network dynamic visualization: network layout, network attribute visualization, and user interaction [4; 8]. After the development over several years, scholars have also made many contributions concerning the three aspects presented above. A list of the common methods for the realization of dynamic visualization and visual analysis is shown in Table 1.  
As shown in Table 1, the network layout methods mainly include the Force-Directed Algorithm (FDA) layout and its improvements. The methods of network attribute visualization mainly include the animation method and the timeline method. The interactive methods mainly include the fisheye view method, the focus and context method, and the multi-view association coordination method. In this paper, we refer to and improve the methods described above to implement the SINDVis. Therefore, the specific contents of the above methods are not discussed in this section too much. In addition, development of dynamic visualization at home and abroad has been carried in probleme work [13], and this section does not elaborate on them further.