in operation field considering the land cover. 
Slope gradient 
The slope gradient is calculated by the degree 
of slope distribution in an operation field. It is used 
in estimating mobile routes, development of roads, 
and selection of communication sites. Slope rates is 
taken as the maximum value among the 8 direction 
gradients in 3 x 3 windows. 
Atmospheric phenomena 
Atmospheric phenomena is a critical factor 
which restricts preparing an operation and making a 
plan in the battlefield. In the present study, we 
simplify the time-varying change of atmospheric 
phenomena once a day and collect respective 
representative value, to establish them as a database. 
The observed and reported atmospheric phenomena 
are classified as temperature, precipitation, humidity, 
wind, and fog. 
Field mobility 
After analyzing the field mobility for mobile 
weapon considering slope gradient, slope aspect, land 
cover, and soil simultaneously, we use the results in 
making a operation plan and combat capability. The 
analysis logics which was developed by the Korean 
Army Headquarters not only uses special map for 
terrain analysis, but calculates slope gradient, slope 
aspect, etc using accurate digital data. Thus, it 
guarantees more elaborate results than any other 
previous algorithms. 
CONSIDERATION FACTORS 
To analyze and evaluate an RA, following six 
factors are computed and weighted integrating input 
data layers described above. 
Observation/Field of fire 
Each candidate RA modeling is divided into 
subsections with a uniform length of 1 km from the 
start point to the final destination and the 
observation line is determined for each of subsections. 
Additionally, we developed the more realistic and 
accurate two-dimensional(2D) computational method 
which calculates observation/field-of-fire considering 
human's visible angle. Since men are the subject of 
observation, it is desirable to include the characterists 
of the human's vision system in analysing visible 
lines. In the previous method, we set a visible line 
perpendicular to the base line of the observer 
and calculate visibility in one dimensional direction. 
International Archives of Photogrammetry and 
  
Figure 2. GIS data layers for the RA selection and 
evaluation. (a) network of major roads (b) covered 
area (c) concealed area (d) major rivers (e) mobile 
space (f) slope gradient 
In this method, we are able to obtain more realistic 
and accurate line-of-sight data implementing 2D 
fan-shape analysis algorithm which conforms the 
human's instant visible habit. Thus evaluation 
mark(EM) can be computed with equation(1). 
EM = -area of observation or field of fire (1) 
area of RA 
Covered/Concealed area 
Average rate of covered/concealed area for each 
candidate RA is computed. 
400 
Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
  
  
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