# Study on Multi-Scale Coral Reef Pore Structure Identification and Characterization
## 5 Feature Region Location Method
### Result Analysis
As can be seen from Figure 15b, the maximum comprehensive similarity value is 0.8216, and the corresponding search matrix is row 17 and column 77, indicating that the comprehensive similarity between the regional image matrix [17; 77] in the mesoscopic image and the micro-image is the highest. As can be seen from Figure 15c, the maximum value of comprehensive similarity is 0.7644, and the corresponding search matrix is row 85 and column 49, indicating that the comprehensive similarity between the regional image matrix [85; 49] in the macro-image and the micro-image is the highest. In order to verify the accuracy of the method in this paper, the key area search results of 10 \(\times\) 10 grid image, the key area search results of 100 \(\times\) 100 grid image and the area where the real extracted image is located are compared. The comparison diagram between the search positioning area and the real sampling area is shown in Figure 16. Figure 16a searches for the sampling area corresponding to the macroscale through the mesoscopic image. Figure 16b is a microscopic image for searching the sampling area corresponding to the mesoscopic-scale. Figure 16c is a diagram for searching the sampling area corresponding to the macroscale through the micro-image. The dark red area in the Figure represents the real sampling area, the pink area represents the 10 \(\times\) 10 grid search positioning area, and the green area represents the 100 \(\times\) 100 grid search positioning area. As can be seen from Figure 16a, in searching the sampling area corresponding to the macroscale through the mesoscopic image, the 100 \(\times\) 100 grid is used for search, and the calculated positioning area is closer to the real sampling area. As can be seen from Figure 16b, in searching the sampling area corresponding to the mesoscopic-scale through the micro-image, a 100 \(\times\) 100 grid is used for search, and the calculated positioning area is closer to the real sampling area. As can be seen from Figure 16c, in searching the sampling area corresponding to the macroscale through the micro-image, the 100 \(\times\) 100 grid is used for the search, and the calculated positioning area is closer to the real sampling area. This is mainly because the real sampling size area is small, and the 100 \(\times\) 100 grid division is carried out more than the 10 \(\times\) 10 grid division, and the divided search area is closer to the real area. In taking the macroscale image as the search target image, the reliability of taking the mesoscopic-scale image as the target area is higher than that of taking the micro-scale image as the target area, mainly because the mesoscopic-scale is closer to the macro-scale pore structure characteristics than the microscale. Through this comparison, the feasibility and correctness of this method are also verified. Figure 15: 100 \(\times\) 100 grid multi-scale pore structure image search diagram. **(a)** Macro mesoscopic search; **(b)** Mesoscopic micro search; **(c)** Macro micro search. In addition, because the grid search method in this paper combines pore distribution characteristics, pore change characteristics, pore fractal characteristics and pore shape characteristics, in order to verify the advantages of this method, this method is compared with the grid search method considering only single pore characteristics, and 100 \(\times\) 100 grid search is realized through a similarity matching algorithm. The search location area corresponding to different methods is shown in Figure 17. Figure 17a is a search for the sampling area corresponding to the macroscale through the mesoscopic image. Figure 17b is a microscopic image to search the sampling area corresponding to the mesoscopic-scale. Figure 17c is a microscopic image to search the sampling area corresponding to the macroscale. The dark red area represents the real sampling area. The green area represents the 100 \(\times\) 100 grid search and location area processed by this method.