Z/| Imaging Image Translators and Raster Utilities in order to 
prepare them for use within the ImageStation application suite. 
As each photo is created, it is associated with a particular 
remote sensor type, and initial RPCs are calculated for it and 
stored in the project photo file. The support data files for each 
image are copied from their original locations to a subdirectory 
within the project directory. An initial grid file is also produced 
and stored with the support data files. A rational function 
bitmap file is also associated with a photo when it is created. 
This bitmap file specifies which terms in the rational 
polynomial functions will be used, and which corresponding 
parts of the RPCs will be calculated by the software when 
working with the photo. 
The final step in project initialization is the collection of control 
and check points. Ground point coordinates are stored within 
the project as  longitude-latitude-elevation triplets. The 
longitude and latitude are represented in 
degrees/minutes/seconds in a  quasi-decimal format 
(dd.mmssssss), and the elevation is represented in meters. 
Control and check points may be entered manually using the 
Edit Control Points command, or they may be imported from 
files in a variety of formats. When importing, it is possible to 
specify a coordinate system and/or units for the incoming 
points that is different from that of the project. In that case, the 
points will be converted into the project WGS84 ellipsoidal 
system and units as they are imported. 
It is also possible to capture control and check points using map 
photos. Map photos are orthoimages or scanned topographic 
maps that have been geo-referenced. If map photos are created 
3 ImageStation Digital Mensusation - Project: C:\Documents and Sellings\jbiard\Deskiap\Zl Projects\QuickBird\PhoenixAZ2a 
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within the project, they can be used to obtain control and check 
point coordinates, either with or without the use of digital 
elevation models (DEMs). The control and check point 
coordinates are automatically converted from the coordinate 
system of the map photo to that of the project. 
3.2 Measurement and Triangulation 
After the project has been initialized, the Multiphoto command 
is used to measure control, check, and tie points on the project 
photos (Figure 2). The Multiphoto command allows the user to 
display multiple photo images simultaneously, and to display 
stereo views of overlapping regions. Unmeasured control and 
check points are displayed on the images in the locations 
predicted for them by the photo RPCs. The user measures the 
actual locations of the control and check points within the 
images, and measures tie points by marking the locations of a 
ground point in multiple images. 
Once control, check, and tie points have been measured, the 
Satellite Triangulation command can be used to perform 
triangulations on photos, either singly or in blocks (Figure 3). 
As mentioned in the previous section, the block adjustment 
engine in combination with the appropriate remote sensor 
modules is used to perform the adjustment of the selected photo 
or block of photos. The Satellite Triangulation dialog displays 
a variety of statistics about the adjustment, as well as detailed 
lists of the residuals for the photo and ground points. If the user 
is not satisfied with the results, points may be withheld or 
deleted on the photos or on the ground, and the adjustment can 
be repeated. If the user decides to accept the results, new photo 
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Figure 2: Multiphoto Dialog 
  
  
   
   
   
   
    
   
    
   
   
   
    
   
       
    
   
   
    
  
  
  
   
    
     
     
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
   
   
   
  
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