# Sino-InSpace: A Digital Simulation Platform for Virtual Space Environments
## 3 Key Technologies
### Visualization Scenario Organization  
The visualization scenario refers to the organization of the geographical environment, entity and space environment elements, and space activities, which belong to the geographical scene. Traditional cartography and GIS are commonly used to express the static information and temporal relationship. The visualization scenario focuses on multilevel and multidimensional information regarding time, location, participants, events, processes, and phenomena, among others [38; 63]. The visualization scenario organization in this study was based on two levels: logical modeling and data modeling, as shown in Figure 7.  
Figure 5: Description for a BeiDou navigation satellite. Attribute information does not generally change. Structure information is partially related to time because sometimes the components need to adjust. Position and attitude information is always related to time.  
Figure 6: Entity object model design. The action object derives from the component or geometric model itself.  
The static structure and relationship of the visualization scenario data were described by defining the specific terms using the Unified Modeling Language (UML) diagram. As in the previous case, SpaceScenario contains three main nodes: GeoEnvironment, SpaceEnvironment, and Object. The type, structure, data constraints, and the correspondence and association between different levels of the hierarchy were described. In GeoEnvironment, the path gives the file system information for the config file of the geographical data, which contains the details of pyramid tiles (e.g., region, tile size,  
Figure 7: Scenario organization and modeling based on Unified Modeling Language (UML) and eXtensible Markup Language (XML). **(a)** UML diagram of the visualization scenario. **(b)** XML data of the visualization scenario. Timeline is used as an example; its logical model includes the start time, end time, and time step. The datatype of the start time and the end time is defined as dateTime, while that of the time step is Double. XML content was filled according to the field data type, which can be stored in the local file to be accessed later. Furthermore, Timeline was also the part of the Ephemeris and Action classes with the corresponding relationship of 1 to 1.  
tile level, and storage location). In SpaceEnvironment, the path and model indicate the source of the space environment data. The former refers to the directory of the environment data file and the latter is the model used for calculation. The Object node has three child nodes: Model, EphemerisList, and ActionList. These nodes depict the geometric model, ephemeris, and behavior model in Section 3.3. In Model, filepath means the path of the object geometric 3D model file. InitialTranslate, InitialAngle, and InitialScale describe the initial state of the object geometric 3D model. In EphemerisList, several Ephemeris nodes may be contained and each one represents a track. Here, the orbit type of \"BEIDOU 1D\" satellite is TLE. ActionList also comprises more than one Action node, which records the change of translation, rotation, and size.