## 3 Result and Discussion
### Extraction of the Final Regenerative Areas
#### 3.3.1 Intersection with the Results of the Vegetation Indices  
The regeneration area extracted from the vegetation index was calculated using the ArcGIS program, and since the area of the regeneration area polygon is extracted based on the coordinates, an accurate area can be calculated. To verify our findings, the method of obtaining ground truth data is the most appropriate. However, in the study area, all of the forest fire areas were cleared through artificial restoration. Since we cannot obtain the ground truth data, we performed verification using NBR. The regenerative area according to NDVI was 1,782,017 m\({}^{2}\), which was approximately 77.8% of the NBR-derived area of 2,291,425 m\({}^{2}\). It is shown in Figure 8A. The regenerative site according to EVI was 1,386,861 m\({}^{2}\), which was approximately 60.5% of the area obtained using NBR. It is shown in Figure 8B. The area of vegetative regeneration according to SAVI was 1,899,166 m\({}^{2}\), which was approximately 82.9% of the area according to NBR, as shown in Figure 8C. Figure 8D is an image of all three vegetation indices and NBR overlapping. The overlapped area is colored in brown and represents the finally derived vegetation regeneration area. The area of the final regenerative region is approximately 881,558 m\({}^{2}\), indicating that approximately 12.3% of the total area regenerated. The results using the three vegetation indices showed that most of the clusters formed by NDVI, EVI, and SAVI were consistently identified as vegetative regeneration sites. Furthermore, to determine the vegetative regeneration sites, the final regeneration area \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **NDVI** & \multicolumn{4}{c}{**EVI**} & \multicolumn{2}{c}{**SAVI**} \\ \hline
**Cluster** & & & & **Cluster** & & **Cluster** & \\
**Numbers** & **Min** & **Max** & **Numbers** & & **Min** & **Max** \\ \hline
1 & 0.51978 & 0.79164 & 1 & 0.47128 & 0.78493 & 1 & 0.77957 & 1.18735 \\
2 & 0.40143 & 0.51977 & 2 & 0.33159 & 0.47125 & 2 & 0.60204 & 0.77956 \\
3 & 0.30017 & 0.40141 & 3 & 0.20438 & 0.33153 & 3 & 0.45015 & 0.60202 \\
4 & 0.21305 & 0.30015 & 4 & 0.12036 & 0.20437 & 4 & 0.31957 & 0.45015 \\
5 & 0.09828 & 0.21305 & 5 & 0.07111 & 0.12036 & 5 & 0.14746 & 0.31956 \\
6 & \(-\)0.09949 & 0.06206 & 6 & 0.03244 & 0.07111 & 6 & \(-\)0.14741 & 0.14927 \\
7 & \(-\)0.62056 & \(-\)0.09957 & 7 & \(-\)0.42895 & 0.03243 & 7 & \(-\)0.93062 & \(-\)0.14900 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Optimal cluster pixel range for the vegetation index. Figure 8: Match between the vegetation indices and NBR: (**A**) NDVI, (**B**) EVI, (**C**) SAVI, and (**D**) overlapped region of the vegetation indices and NBR. (green color layer in Figure 9) was derived by extracting the intersection of the areas computed by the different indices. The background of Figure 9 is the true color image newly taken on 14 April 2020. When overlapped with the vegetation regeneration layer extracted in this study, it was found that some vegetation areas coincide, as shown in the blue square region in Figure 9. In contrast, in the area marked with a red square, it was possible to observe with the naked-eye that all trees were cut to proceed with the reconstruction project, which can be judged as an area where plants were removed even though plant regeneration was possible. Areas extracted in the form of small irregular patches can also be identified as regenerated areas. However, they may represent the growth of weeds, not clusters of vegetation. The regenerated site's final area was 881,558 m\({}^{2}\), representing approximately 12.3% of the total area affected by the forest fire. The dNBR fire severity calculations showed that the regenerated area had a moderate-low or low damage severity. The dNBR fire severity table showed that vegetation could be restored to normal levels. In Figure 9, NDVI was found to represent a regenerative area when the image pixel value was approximately 0.62 or higher.