left 
camera 
  
  
  
right 
camera 
  
Photo.1 original photo 
  
  
Photo.2 Rectification process 
  
E 
  
  
con 28 
Photo.3 stereo matching process 
3.2 Electronic Still Camera 
  
The digital still cameras are high-resolution cam- 
eras capable of recording the pictures taken in the 
form of digital data. In comparison with conventional 
cameras they have advantages such as that 1) there 
is no need to process the films, 2) there is no need 
for A/D conversion, 3) the picture quality does not 
deteriorate with time, and 4) there is no deterior- 
ation of the picture quality due to copying. The ac- 
tual procedure for taking pictures with the digital 
still cameras is the same as with conventional came- 
ras. The pictures can be reproduced instantaneously 
by connecting the camera to a CRT, allowing the pat- 
rol results to be used immediately for holding cons- 
ultations and giving instructions. The specifications 
of the cameras used in the study reported here are 
given in Table. 2. 
38 
3.3 Site Graphical Information System 
  
À system has been developed with which the plan 
views of the site can be displayed on the personal 
computer screen by simply reading the maps with ima- 
ge scanners and inputting the latitude and longitude 
of the control points and the reduction scale. The 
GPS positional measurement results can be overlaid 
on these plan views. Since this system facilitates 
the input of local cartographical information, allo- 
wing the site patrol systems to be put immediately 
into operation at any given site, it is hoped that 
the system will see general-purpose application at 
each office. On the personal computer screen, it is 
possible to also divide the plan views into 16 sect- 
ions and to obtain enlarged pictures of each of the- 
se sections. 
= 
~~ 
= 
z