# SINDVis: User-Centered Dynamic Interactive Visualization System for Space Information Networks
## 1 Introduction  
There are multiple types of network systems in human and virtual societies [1], such as communication networks, social networks, urban transportation networks, cooperation networks, trade networks, and command and control networks, etc. In fact, regardless of people's livelihood needs, or military applications, most human beings are currently greatly dependent on networks. With the rapid development of science and technology, aerospace has gradually become the focus of many countries, especially in terms of the modernized armament game. The space information network (SIN) [2] plays an extremely important role in this game, and the major aerospace countries of the world are actively exploring and conducting related research [3]. As a huge, complex network system, the SIN has some typical characteristics, such as complexity, heterogeneity, and heterogeneity as well as being limited, multilayer and, most obviously, dynamic [4]. The dynamic characteristic of SIN can be subdivided into time-varying aspects in the time domain and space-varying aspects in the space domain. For SIN, because the time-varying and space-varyingcharacteristics are simultaneously present, the irregularity and instability of the network topology is greatly increased, and this also brings many challenges to the construction, management, and use of SIN. In recent years, with the support of the National Natural Science Foundation of China, scholars have made many research achievements regarding the top-level design of SIN architecture, the theories and methods of high-speed transmission, and the sparse representation and fusion processing of space information [5]. However, through a comparative analysis, we identified that the following problems still need to be solved. **Question 1. **_Although there are some technical schemes for SIN architecture, there is no effective demonstration system or integrated platform to show the concrete structure of SIN in the entity domain. As we know, there are a number of simulation platforms, such as the STK (Satellite Tool Kit) and SaVi. However, both of them are based on the client/server (C/S) architecture implementation, and the SaVi is mainly applied to academic verification. Therefore, the STK and SaVi are inconvenient for application and promotion. For multi-class users, it is very important to determine how to demonstrate effectively the composition structure and operation laws of the SIN in the entity domain._  
**Question 2. **_With the increasing demand for the construction and development of SIN, its scale is expanding, and its composition structure is becoming more and more complex. For users who come from the department of construction and management of SIN, it is necessary to understand the system structure of SIN with scale enlargement. Meanwhile, we also need to understand the topology structure model of SIN and explore the key nodes and core links of the SIN. All of the above aspects are very important for maintaining normal operation and daily management. At present, there is no relevant molding platform to show the topology structure and demonstrate its topology evolution laws of SIN in the topology domain._  
For the above questions, we introduce some relevant techniques and methods of visualization, and design and implement a dynamic interactive system of SIN, named SINDVis. The system can satisfy multiple needs of multi-class users at the same time. The rest of the paper is organized as follows: In Section 2, we explain the related work, including the concepts and architecture of SIN, the technology principles of dynamic visualization and visual analysis, and multi-class users' characteristics. In Section 3, we build the architecture of SINDVis, analyze the specific functions of the visual views of GeoView and TopolView, and discuss relevant theories and methods of realizing the above views. Section 4 presents the verification of the instances, and we use a typical SIN as an example for the implementation of GeoView and TopolView. Section 5 discusses the verification results.