International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
  
+ Farm Road 
  
le nu 
  
Irrigation canal 
  
  
Paddy field 
(a field lot) 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
e 477 P mae canal 
*«— Farm Road 
  
2.3 Terrain feature candidates decision making rule 
e Paddy field almost without damages 
Levee of paddy fields should be above the inundated 
water surface. Then after cutting the SAR data off at the 
threshold of appropriate value and making binary images, 
some dilation operations are performed for filling the interval 
areas of levees in improved paddy fields as non-damaged 
fields. The number of iteration should depend upon the 
width of the paddy fields, because the land-improved paddy 
field has the shape of rectangle. And the levee, farm lane, will 
run along the long side of the rectangle. 
e Most likely flooded water surface 
The region of the low backscattering intensity level can 
be most likely large water surface. This time, threshold 
method is adopted for getting the candidate of large water 
surface. 
3. CASE STUDY IN THAILAND 
3.1 The proposing method of terrain feature recognition 
for SAR imagery employing spatial attributes of targets 
The combination of dilations after erosions is called an 
“opening” operation. Another combination of dilations 
followed by erosions is a "closing" operation. “Open 
operation” has the effects of removing pixel noise. “Closing” 
used to bury small holes or narrow dents and to connect 
603 
Plane figure of paddy rice fields after farm land improvement 
together with the broken connected components (river or 
something). 
SAR signal intensity for each pixel includes some 
interactive information between microwave and terrain feature 
on the ground. Then we can examine SAR images applying to 
morphological processing procedures above mentioned. 
3.2 Terrain feature candidates decision making rule 
e Paddy field almost without damages 
Levee of paddy fields should be above the inundated 
water surface. Then after cutting the SAR data off at the 
threshold of appropriate value and making binary images, 
some dilation operations are performed for filling the interval 
areas of levees in improved paddy fields as non-damaged 
fields. 
e Most likely flooded water surface 
The region of the low backscattering intensity level can 
be most likely large water surface. This time, threshold 
method is adopted for getting the candidate of large water 
surface. 
3.3 Procedure of case study in Thailand 
The following picture, Fig.4, shows the flow chart of the 
computational method of flood extent detection.