# SINDVis: User-Centered Dynamic Interactive Visualization System for Space Information Networks
## 4 Results
### TopolView Implementation
#### 4.2.2 TopolView Function Implementation  
As described in Section 3.2.2, we show the overall structure of the SIN in the topology domain; that is, the entity and connection relationships are mapped to the nodes and the edges respectively to show their relational structure. Corresponding to Section 4.1.2, it is assumed that the SIN consists of the following components: three GEO satellites (ref. : GEO_1-GEO_3), six MEO satellites (ref. : MEO_1-MEO_6), five LEO satellites (ref. LEO_1-LEO_5), 10 hot air balloons (ref. : Hab_1-Hab_10) and two ground stations (ref. : F_1-f_2). This is in accordance with others in terms of the connection rules. A formation schematic diagram of the initial topology is shown in Figure 16.  
Figure 16: The process displays of dynamic networking of SIN: (**a**) The basic elements of SIN at the initial moment; (**b**) the formation process of the MEO/LEO-layer satellite system; (**c**) the formation process of satellite systems; (**d**) the process of prototype formation of SIN. Figure 16 shows the dynamic networking of SIN in the SINDVis system from a topology domain perspective. Based on the architecture of the SIN that was discussed earlier, the basic elements of the SIN, including the GEO, MEO and LEO satellite systems and ground stations, are presented at the initial moment in diagram (a), and we assume that the internal connection relationship is established. Figure 16b demonstrates the process of connecting the MEO satellite system and the LEO satellite system to form a MEO/LEO-layer satellite system. Figure 16c shows a three-layer, interconnected SIN consisting of the GEO-layer satellite system, the MEO/LEO-layer satellite system, and the ground station, and to solve the problem of the Near Space layer, the Hab group is added to represent the Near Space layer information system. As shown in Figure 16d, the Near Space layer information system is connected to the entire network, and then the prototype of SIN is formed. Next, we show the specific evolution of the SIN TopolView and demonstrate the dynamic interaction capabilities of the SINDVis system. In Figure 17, Figure 17a shows the interactions between the user and the node. When the user puts the mouse over a node, the details of the node appear at the top right of the page, including the node name, node degree, output stream, and input stream. The detailed information is hidden when the mouse is moved. Figure 17b shows the interactions between the user and the edge. When the user puts the mouse over a connecting edge, information about the edge of the details, including the target node and the source node's name and the connection level appear in the upper right of the page. The detailed information is hidden when the mouse is moved. Figure 17c shows a translation of the interactive function. To display only the details of the GEO layer on the page, the other parts of the network can be translated out of the visual page. Figure 17d shows a zoom function based on Figure 16d, that is, it displays details on the same size page by scrolling the mouse to zoom in the page. Figure 17: Interactive function displays of the SIN TopolView: (**a**) the interactions between the user and the node; (**b**) the interactions between the user and the edge; (**c**) the translation interaction function; (**d**) the zoom interaction function. By combining the content shown in Figures 16 and 17, the partial functionality of the TopolView for the SINDVis system can be described as a whole, as follows:  
* **Description 1**: Both of Figures 16 and 17 are views with the same network structure, and due to the limitations of the network structure itself, it is difficult for a user to understand the four-layer architecture of the SIN through Figure 16d. Therefore, we constrained the network nodes at different levels by introducing clustering coefficients. For the four-layer structure in SINDVis, the effect of Figure 17a is achieved by setting four different constraint values.