The following two triplet methods were proposed and compared 
each © 
(1) 
(2) 
Ray N 
Fig. 
  
ther and with the conventional method. 
Independent Check Method 
Two pairs of stereo matching, that is, ray 
and No.3 are independently matched, with use 
The error of two computed heights, Z12 and 
checked as shown in Figure 1. If the error 
an allowed value, the stereo matching can be 
reliable. If the error is large, the stereo 
be repeated until the criteria is satisfied. 
Simultaneous Check Method 
No.1 and No.2 
of 3x3 window. 
223 is 
Z is less than 
considered 
matching will 
Three rays are simultaneously matched under the condition 
that three rays should be intersected at a point, as shown 
in Figure 2. 
Two windows of different size, that is 3x3 
used to check the error of height. 
o.1 Ray No.2 Ray No.3 
  
  
  
  
  
and 9x9 are 
  
1 Independent Check Fig. 2 Simultaneous Check 
Method Method 
226