Figure 4c. Axios delta — 3x3 high pass filter 
  
Figure 4d. Axios delta — Sobel operator 
DISCUSSION — CONCLUSIONS 
Geomorphology, geology, soils, land cover, land use and 
climate are important factors for the formation of drainage 
network, catchments and estuaries of a river. These factors in 
combination with marine influences (waves, sea currents) affect 
delta formation. 
In this paper, we search through the possibilities of visual 
interpretation of primary image data and enhanced image data 
on the study of coastal areas of Thessaloniki and particularly on 
Axios and Gallikos delta area. 
Visual image observation — image interpretation (photo- 
interpetation) results in important information about the form of 
estuaries, Axios bird-foot delta, the formation of lagoon at 
Gallikos estuaries, landcover outside the riverbed, deposition 
areas of the transported material and for other features as roads 
and cultivated land. Digital image processing and particularly 
image enhancement make the above features more interpretable. 
The results of visual image interpretation of SPOT satellite 
image and after image enhancement are very interesting and 
useful for the theoretical and practical study of delta areas. 
The study of coastal areas are of great importance for the Greek 
area (mainland — islands), concerning settlements, tourism, 
culture, maritime transport, delta formation etc. 
Photogrammetry | — digital image processing and 
       
    
  
  
   
    
   
   
     
   
   
    
   
  
  
  
  
  
  
  
   
    
    
  
  
  
    
   
   
    
  
    
   
    
    
  
  
  
    
   
photointerpetation — image interpretation significantly 
contribute to this study as presented in this paper for the case of 
river delta areas. 
REFERENCES 
ASPRS, 2004. Manual of Photogrammetry, 5^ Edition. 
American Society for Photogrammetry and Remote Sensing, 
pp.416-417. 
Erdas Field Guide™, 2010, Erdas Inc. U.S.A. pp.455, 474, 535. 
Lillesand T.M., Keifer R.W., 1987. Remote Sensing and Image 
Interpretation. 2" Edition, John Wiley and Sons, Inc., pp. 176- 
179. 
Zuidam R.A., Zuidam-Cancelado F.L, 1979. Terrain analysis 
and classification using aerial photographs. ITC, The 
Netherlands, pp. 166. 
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