321 
It is of great importance for the hardware to be as standardized 
as possible so that maintainance and service can be easily carried 
out. Using to the maximum the large scale integrate circuit (ISI) 
can greatly reduce the nember of connections and thus increase the 
reliability to a great deal. 
The CRT and u-80 printer shown in Figure 2 can be excluded from 
the system when the development comes to a perfect halt, which 
means the cost of the orthophotoprojector system will get even 
lower. 
This instrument looks as if it were based on rectification by li- 
near elements, but in reality, it is based on that by area ele. 
The reason for this is that the registration interval (DEM'S) in 
y direction is exactly the same as that in x direction, which takes 
a form of a square. There is no need to favor y direction than x, 
since registrations along y direction are much thicker. 
(2) Main Factor for Determining the Slit Width -- Second Eleva- 
tion Difference. ; 
Projection from a photograph onto a tilted ground surface means 
perspective transformation P, and due to the relief P, is not a 
constant matrix. The projection from the ground surface onto the 
horizontal plane (map) is an affine transformation A. The princi- 
ples of geometry tell us that to project directly from a photo- 
graph onto a map the new perspective transformation formula Po 
A* P, Should be used; but we approximate P5 by & Similarity trans- 
formation (near axial beam) only, of course this approximation is 
limited, what is remarkable was the error which would result from 
the second elevation difference in the slit. To show this the 
Figure 3 is provided.