Fig. 15. Detected ice sheet margin using a digitized aerial 
photograph draped over Fig. 5. 
  
— — SAR (August 20, 1992) 
ae photograph (July 10, 1985) 
—- SPOT (May 30, 1988) 
  
    
  
  
  
Fig. 16. Comparison of ice sheet margin maps detected 
using three different sensors. 
5. CONCLUSIONS 
Steps for ice sheet margin extraction were presented by 
integrating several different algorithms and applying 
them to different sensor data sets. By comparing the ice 
sheet margin detected using different data, the following 
conclusions are reached. 
  
632 
The ice sheet margin is successfully detected using 
an automatic approach. 
Each sensor (SAR, SPOT, aerial photograph) has , 
different image signature near the ice sheet margin 
which causes an apparent fluctuation in the ice shes 
margin. 
Uncertainty of digital elevation model causes 
displacement of the margin up to several hundred 
meters in geocoded and terrain corrected SAR 
imagery. 
Over a 7 year period the ice sheet margin north and 
south of the Jakobshavn glacier fluctuates by less 
than 350 m. The calving front fluctuates up to 23 
km. 
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