## 4 Results and Discussion
### Discussion  
In the rapid urbanization context, cities are continuously expanding, leading to difficulty for urban planners to evaluate the development of built-up areas and their parameters, such as the BCR. The proposed DL-based approach to measuring the BCR has been tested and evaluated through an assessment to monitoring the coverage status of urban areas at different scales. Through the accuracy assessment of the DL-based method in the BCR calculation, the potential of this approach has been revealed. Utilizing DL for the building footprint generation speeds up the BCR measurement and prevents errors and effort for manual mapping. Moreover, by displaying the coverage ratio of each block, a complete and quantitative image of the shape and spatial organization of the research area's urban environment was generated. Consequently, congested areas could be visualized easily, allowing decision-makers to identify over-construction blocks. This means that by comparing the extracted BCR with the legal BCR, tracking legal BCR compliance is possible. By indicating potential over-construction regions, planners can consider suitable redevelopment plans to control the BCR in regions such as industrial zones, business parks, and residential areas. Urban density management, therefore, is more effective and proactive. Since drones can acquire aerial images quickly and at a lower cost than satellite imagery, the BCR extraction from drone images based on DL could be more accessible for decision-makers charged with carrying out urban density assessments. Suppose, for example, that the accuracy of the DL-based method can be improved. In that case, aerial inspection using a DL-based method could potentially replace fieldwork for measuring the coverage ratio of built-up areas in today's rapid urbanization context, which requires frequent updates to track our ever-changing urban environments. The BCR calculation based on DL has the potential to become a vital tool for urban management to support urban planning decisions. This tool will allow policymakers to perform city-wide building coverage investigations to identify over-developed regions and select low-density areas for upgrading. The proposed application of the DL-based method in urban building coverage survey is shown in Figure 8. The BCR status of certain areas can be measured by utilizing the proposed DL-base method. Then, the extracted BCR status can be visualized by using data visualization tools to monitor the BCR. Consequently, decision-makers can check whether the referenced areas exceed the legal BCR so that further actions can be considered. Besides, the BCR and the FAR can be used for urban density analysis. This provides a foundation for population estimation and infrastructure development plans. In countries that enforce urban regulations to control legal BCRs (e.g., Japan, Korea, and Vietnam), compliance tracking is crucial for urban management to prevent over  
Figure 8: Proposed applications of the new BCR calculation approach based on DL for urban management and urban density analyses. construction. However, it is mostly carried out as part of the application process for building permits and completion. This means that encroachment construction that takes place after a building enters operation might be missed, leading to a BCR violation [13]. The BCR tracking after construction through site surveys is often difficult due to land accessibility and being time-consuming and costly. In light of our proposed DL-based method and drone mobility, acquiring blocks and parcels' BCR seems easier than conventional methods in terms of time, labor, and cost. Thus, monitoring the BCR at a city scale is possible to track legal BCR compliance, contributing to improving urban management. The use of aerial inspections to extract the BCR in urban areas might fast become a viable method for urban density analysis and management. However, there are some obstacles to the proposed DL-based approach that need to be considered.