International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004 
  
This allows many types of acquisition modes : 
-  Multi-spot mode, (Fig. 11) where the satellite 
acquires many targets around the satellite ground 
track, even in fore and aft stereoscopic mode if 
required 
  
  
Fig .11 Multi-spot mode 
- . Covering or Mosaic mode, (Fig. 12) where swath 
enlargement is obtained by contiguous strips, even 
in East/West direction of acquisition 
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tu 
  
Fig 12 Mosaic mode 
4.8.2 Mission capabilities have been studied at CNES using 
a mission simulator. The mission simulator processes the 
system programming loop and allows the measurement of 
mean acquisition capability for a world wide annual order 
book, and of instantaneous acquisition capability for standard 
daily programming requests. 
A an example the following situation has been analysed, 
corresponding to a possible mission over Europe : 
- . 40 monoscopic targets of 15 km of diameter to be daily 
acquired, over an overall area of interest of 1000 x 1000 
km? 
In this case (Fig. 13), 24 targets over 40 have been acquired 
in one path with 20° inclination access authorized. 
Only a few more (27) can be acquired if the authorized 
inclination access is extended to 30°, due to the extensive 
area of the theater. 
  
Figure 13: Instantaneous performances with 20° access 
4.8.3 Stereoscopic capabilities 
The high agility at low angles enables low B/H stereoscopic 
acquisitions with rather advantageous lengths. 
Table 14 shows the maximum length of stereoscopic 
coverage acquired from the same orbit with different B/H, 
either for stereo pairs or for triplets. 
Tri-stereo consists in acquiring an image triplet with the 
central image acquired in vertical sighting in the pitch 
(fore/aft) direction. This type of acquisition becomes 
increasingly important where urban information acquisition is 
concerned, as it is used both to restore terrain contours (using 
the stereo conditions) and to obtain exhaustive object images 
by avoiding hidden faces using vertical sighting. These image 
acquisitions are particularly useful given the very low 
     
     
   
   
   
    
    
    
  
  
  
  
    
     
   
   
   
    
    
    
   
  
    
   
  
     
   
  
   
    
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