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32 Feature point matching under the moving Z-Plane 
constraint 
Focusing on experimental images, this paper adopts the 
Forstner operator to extract feature points in all images. The 
number of feature points extracted in image L1, image L2, and 
image L3 are 34343, 32901, and 28053, respectively. 
(D Initially matching of the best grid cells. It moves the plane 
from high to low, and matches the grid cells with number =3 
at each height position, the matching results of grid cells on 
Z=31 position is shown as Fig. 3. The threshold of ANCC is 
0.85 in the grey similarity measurement calculation. The result 
of initially matching of the best grid cells is shown as Fig. 4, 
and the number of the homologous points is 3009, which is 
denoted by red cross, and the corresponding positions in the 
grid cell is shown as Fig. 5. 
  
  
  
  
  
  
   
L3 L3 
Figure 3. The matching results of grid cells as number-3 on 
Z=31 position 
Figure 4. The matching results of the best grid cells as 
Number-3 
  
  
  
  
    
    
     
    
  
    
  
   
  
   
   
   
  
   
    
  
  
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
    
   
   
   
  
(2) Matching of the second-best grid cells. After the matching of 
the best grid cells, this algorithm matches the grid cells with 
number = 2 , and the number of successfully matched grid cell 
is 5853, which corresponds to the homologous points in 
different images (Fig. 6). This paper adopts different colors to 
express the matching results of different images combination, 
for example, the yellow dots express the matching result of 
image L1~L2, the blue dots express the matching result of 
image L2~L3, and the red dots express the matching result of 
image L1~L3. The number of the homologous points obtained 
by matching with different image combination separately are 
2871, 2566, and 416. Obviously, the longer baseline among 
multi-view images, and the bigger intersection angle, the more 
difficult of the matching. The ellipse area in image L1 and 
image L2 in Fig. 6 shows that this area does not match the 
homologous points because of the occlusion in the image L3 in 
the initial matching process. Through the matching of the 
second-best grid cells, this algorithm automatically selects the 
image L1 and image L2 to match according to the projection 
rays, and obtains the correct matching results, as shown in the 
homologous points by yellow color in the ellipse area, which 
effectively avoids the influence of the occlusion area in image 
L3. 
    
    
    
      
     
    
    
    
    
      
   
L3 L3 
Figure 6. (left) The matching results of the second-best grid 
cells as number-2 
Figure 7. (right)The final results 
After the matching of the best grid cells and the second-best 
grid cells, the total number of the successfully matched grid 
cells is 8862 (Fig. 8), which corresponds to the homologous 
points in different images (Fig. 7). The meaning of different 
colors and different signs is the same as the front. It can be see