## 3 Results
### Practical Application and Spatial Accuracy Evaluation of the Prototype System  
A prototype system was constructed and implemented, serving as a MIDA application testbed. The system adopts the browser/server architecture, i.e., the server side was developed with Visual Studio C#, the client side was developed with Vue.js, and the 3D engine on the client side is Cesium. At present, the developed webGIS system was only deployed and accessed in a local area network (LAN) concerning data security. The platform was designed as an account-based application. Thus, user registration was required to access the full functions of the system. After logging into the website, certain registered users were authorized to perform the system's function. On the other hand, a well-designed interface could resolve some of the complexities of the proposed system, making it more useable and, thereby, widely accepted and adopted by the users. Therefore, this study focused on designing interactive and user-friendly GUIs that allow experts and non-experts to operate the system easily. Different modules structure the GUIs, making the system easy to use and expandable. Figure 14 presents the main GUIs of the web-based MIDA platform. In particular, Figure 15 illustrates the enlarged local 3D real model of an industrial square provided by a platform with a bird-view mode. The GUIs comprised a map viewer, various GIS entities and analysis results visualization, and GIS analysis tools, mainly including some basic GIS tools, a coordinate conversion tool, and the developed MIDA-related functional modules. The map viewer was a Cesium-based 3D virtual globe that provided a WGS84 spatial reference and enabled intuitive geo-visualization of the analysis results and multi-source geospatial data on a default base map (e.g., satellite images) obtained from the OGC's WMS. The developed functional components were docked at the upper-left of the map viewer. The model datasets, including the 3D photo-realistic model, 3D virtual model of power corridors, and other base maps, were contained in the \"Data Layers\" component and used as the background data layers. Some basic GIS tools, including point, distance, area, and orientation angle measurement, could facilitate the manifold and practical applications. It should be noted that the tool of  
Figure 13: Photogrammetric processing results for the selected two ROIs. (**a,d,g,j**) are the AT results with different scale combination (yellow or orange points indicates the recovered camera positions). Among them, (**a,g**) are AT results of coarse-scale with fixed-wing UAV, and (**d,j**) are fused AT results by combining coarse- and meso-scale and all scales, respectively. (**b,e,h,k**) are their corresponding local 3D realistic models, and (**c,f,i,l**) are corresponding local details labeled by red rectangles in the middle column. coordinate conversion frequently used in the system was also developed on the client side to realize bidirectional conversion between WGS84 and the SC system. The two important functional modules, namely \"Data Management\" and \"MIDA\", were user interfaces where users could interact with the system. The \"Data Management\" module collects the required GIS entity data and stores it in the MySQL database described in Section 2.6. After all the required GIS datasets were collected and saved, in the pop-up window named \"Data Management\", shown in the left part of the main interface, we can review these data in a data grid table and query them by a predefined filter condition. Also, we can further edit them (modify or delete) to ensure the reliability of the collected GIS entity data. Figure 14: Main interface of the proposed web-based MIDA system. Figure 15: 3D real model of industrial square featured with underground coal mining. After completing the data management operation, the next operation of MIDA can be performed. The steps are as follows. 1.