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Toshiaki Hashimoto 
  
coastal image we ve S original image 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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correlation M 
N 
template (NxN) 
search area (MxM) 
(a) coastal line patch (b) original image 
Figure 3. Procedure for GCP collection 
Sufficient numbers of GCPs are necessary for exterior orientation. Conventionally, the GCP collection has been 
conducted by human interpretation. Such procedure is very time consuming and not proper for daily process. In this 
work, the GCP collection is realized by the template matching. 
In figure 3, two image patches contain coastal lines. One (a) is a template from the Generic Mapping Tool (GMT) 
coastal data (Wessel, P.) prepared in advance, another (b) is a reference image made by the binarization of the original 
Image. The template (a) is selected as a GCP candidate from the GCP library which have to be prepared. In this work, 
the sizes of both patches are determined as m=32 and n=16 through some experiments. 
One scene of the GLI Level 1B1 data consists of 1656 lines and 1236 pixels for 1km product. But the GCP collection 
and the exterior orientation are carried out on the tilt segment basis because the orientation parameters are stable during 
the same tilt angle and more GCPs will be expected from one tilt segment than from one scene. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part Bl. Amsterdam 2000. 145