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The relation between shadow length and height of the object can be expressed in 
the following equations: 
ground range representation: 
slant range representation: 
Sg tg. 0 
h =■ 
Ss. tg .0 
cos. 0 
( 2 ) 
(3) 
Often, however, we are dealing not with vertical objects but with topographic 
slopes. For a slope dipping towards the flightline and with a gradient across the 
flight direction which is smaller or equal to the complement of the depression 
angle, radar shadow in ground range representation will have a length of AgC in 
fig. 4. In this case we have to use the equations: 
ground range representation: 
h- Sg 
tg. 0 + ctg. o 
(4) 
slant range representation: 
h = Ss sin 0 
(5) 
Due to foreshortening, the slope DA appears as DAg in the image in ground range. 
Topographic slopes with an angle larger than the complement of the depression 
angle will have a radar shadow which lies somewhere in between AgC and BC. 
This is dependent of the angle of topographic slope. 
Fig. 4 
Shadow length for a topographic slope dipping under 
an angle smaller or equal to the complement of the 
depression angle towards the flightline. 
Ss for slant range and Sg for ground range representation. 
As this angle is normally not known it will be impossible to find the proper 
relationship between height and radar shadow. However, if we measure the