Figure 3 shows the method to determine the earth's surface 
point sensed by a sensor element in a linear array sensor. 
Point I is the center of projection. Point J is a position of 
sensor element in the linear array sensor. There are about 
4,000 sensor elements in the linear array sensor. The position 
K sensed by the sensor element J can be determined as the cross 
point. cof: the line I-J.-and the DTM,. that is, the “earth's 
surface. The line I-J shows the beam of light from the point K 
on the earth's surface to the sensor element J. This point K 
can be calculated using the successive approximation method as 
follows. 
At first the height of the point K is hypothesized as a certain 
value and the cross point with the line I-J, M, is calculated. 
Then the true earth's surface at the position M, here the point 
N, is calculated and the second height of the point K is 
hypothesized between the points M and N. We can determine the 
approximate height of the point K by repeating this process. 
The point sensed by a sensor element at any time can be 
determined like this and the brightness of that point can be 
determined from the orthophoto image made from the  LFC 
photograph. A JERS-1 simulation image can be made by 
determining the brightness of all the picture elements point 
by point like this. 
T ; ; 
A Center of projection 
Linear array sensor 
Beam of light 
  
  
  
  
  
  
  
DTM 
a, 
| IN A 
Third height 
AZ 2 Ce Second height 
e me, 
Initial height 
M dien 
0 
» m 
0 «t «l1 
Figure 3 Method to determine the earth's surface 
point sensed by a sensor element in a 
linear array sensor 
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