# SINDVis: User-Centered Dynamic Interactive Visualization System for Space Information Networks
## 2 Related Work
### User Feature Analysis  
As mentioned in Section 1, the purpose of designing SINDVis is to assist multi-class users to achieve effective understanding, construction, development, maintenance, and management of SIN. Therefore, users are the core factor of the SINDVis design, and users' requirements determine the SINDVis functions. That is to say, the various functions of SINDVis are designed to meet the multiple needs of multi-class users. Therefore, in order to put the idea of user-centered into practice and to provide guidance for the design and description of SINDVis functions in Section 3.2, this section carries out a user feature analysis of SINDVis.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Network Layout** & **Network Visualization** & **Network Interaction** \\ \hline Force-Directed Algorithm & Animation & Fisheye view \\ Improvement 1 & Timeline & Focus and context \\ Improvement 2 & Fusion of above & Multi-view association \\... &... &... \\ \hline \hline \end{tabular}
\end{table}
Table 1: A list of the mainstream methods of dynamic visualization.  
One of the main indicators for verifying visualization is satisfaction degree of the user's visual experience. The primary indicator and original intention of the SINDVis system was to meet the needs of multi-class users. Therefore, we analyzed the characteristics of the existing users and potential users of the SIN to provide a reference for the development of the system function module. According to the needs of the similarities and differences of SINDVis, the main users were divided into three categories as follows:  
* **USE-1**: (Understanding Class Users). The first-class users are new to SIN, and they do not have much relevant background knowledge of SIN. Meanwhile, they need to have preliminary understanding of the composition and structure of SIN with the SINDVis.
* **USE-2**: (Construction and Development Class Users). The second-class users come from the demonstration and construction departments of SIN, and they have a certain understanding of SIN. However, they need to optimize and improve SIN. Therefore, they not only need to grasp the architecture of SIN in real-time, but also need to understand the evolvement laws and development situation of SIN with the SINDVis.
* **USE-3**: (Maintenance and Management Class Users). The third class users come from the maintenance and management departments of SIN, and they need to grasp the structure and change laws of SIN in real time. Meanwhile, they should grasp the position and relationship of key nodes and core links of SIN in the topology domain and effectively avoid the damage and interference of SIN. In addition, they can effectively maintain the normal operation of the SIN with the SINDVis.  
In short, according to the different needs of users, we divided the SINDVis users into the three categories presented above. To show how different users focus on SINDVis views, we present a tabular representation of how much the user needs to use the SINDVis views. We use \(\bigstar\) to express the users' demands for SINDVis, and a greater number of \(\bigstar\) indicates a greater need for views. The requirements of the users for the views are shown in Table 2. The contents of entity view, named GeoView, and topology view, named TopolView, are discussed in Section 3.2.