3. RESULT AND DISCUSSION 
By interactive visual checking a set of threshold values for 
Landsat 5 TM and Spot 5 HRG were established. The Table 3 
shows the threshold values of band SWIR for all spectral 
patterns. 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
  
  
  
  
  
  
Spectral patterns Landsat 5 TM Spot 5 HRG 
022222 3.0 45.0 
222222 3.5 90.0 
002222 N/A 40.0 
002022 N/A 37.0 
  
  
  
  
Table 3. Threshold values for spectral patterns in Landsat 5 TM 
and Spot 5 HRG sensors 
  
Based on the proposed algorithm and chosen threshold values 
water extraction for the Landsat 5 TM and Spot 5 HRG had 
been carried out. Figure 7 shows result of water body extraction 
of Landsat 5 TM image and Figure 8 displays Spot 5 HRG 
water body extraction. Water body filled by solid red colour 
over 4, 3, 2 colour composites is showed on right sites in both 
figures. The study area on Land sat 5 TM image is larger than 
on the Spot 5 HRG. The study area includes Hanoi City and 
surrounding area. Main water bodies are lakes, ponds, rivers and 
canals. In colour composite SWIR-red, NIR-green and 
Green-blue vegetation appears as green, urban including 
housing, construction appear in purple colour. Clear water is 
showed in dark blue and turbid water in cyan colour with 
different level of brightness depending on sedimentation 
contamination grades. 
EHE 
Figure 8. Water extraction by Spot 5 HRV image (left) and overlay on colour composite (right) 
    
  
  
   
    
   
   
   
     
        
    
      
    
  
  
   
    
  
  
  
   
    
    
   
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