the 
y. 
ffe- 
lated 
erence 
1% 
ls 
f 
| the 
ristics 
a 
s A178 RT 
ned 
RANGE 
  
  
   
  
  
  
10% 3% 5% 10% 
Fig. 2 relative division of orientation of black and white lines on the 
image according to the occurence of linear features in reality 
Significance of the difference is 99 $ 
Seasat SAR 19 aug. 1978. 
for both images. 
This phenomenon complicates the interpretability of linear 
features  fortunately, in a limited way, because of their exceptional 
occurence. 
CONCLUSIONS 
- The visual interpretability of linear features on Seasat 
SAR images has a limited efficiency, especially when it concerns interrupted 
lines. 
- The detectability of linear features on the image depends 
highly on the tonality contrast with adjacent pixels. However due to speckling 
it is impossible to use a relative tonality contrast scale. 
- Although significance is not unambiguously proved, a directio- 
nal selectivity in reproducing linear features seems to exist. 
‘= Although the tonality of features on the SAR images is 
related closely to terrain roughness and to dic lectrical characteristics of 
the phenomena, it can be stated that the tonality of some features changes 
according to their relative orientation. 
25% 
ot A Eee ir re a a