Kunii, Yoichi 
  
      
      
| Figure 1. Original image 
  
(a) Filtering (b) Straight line 
Figure 2. Line Extraction image 
However, there are some useless lines for line tracking in the first line extracted image. Then, the useless lines were 
removed by manual operation in the only first sequential image. 
2.1.2 Optical Flow Estimation: Many optical flow estimation methods have been proposed. The optical flow was 
estimated using the Lucas-Kanade method which has features for correct and fast procedure in this paper (CHIBA, N., 
KANADE, T., 1998.). Lucas-Kanade method is one of the spatial local optimization, and the optical flow by Lucas- 
Kanade method is calculated by following equation. 
  
3 ppm xp aa 
Tx way 
i sí me arY © 
"(0x 2 oy 
where, 
1(p)=1I(x,y,1), J(p)=I(x,y,t + &) 
Furthermore, in order to improve accuracy of the optical 
flow, the optical flow was corrected by hierarchical 
estimation (SATO, M., SASAKI, H., 1986.) and reliability 
function (YOSHIDA, T. et al, 1997.). Figure 3 shows 
optical flow estimation. 
Figure 3. Optical flow estimation 
  
460 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 
  
  
m- — PUT pi peed OY S N = RD