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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
Fig. 3. The difference of the two images provide the points whose 3D coordinates are calculated 
sharper images when used in very close ranges. Proper 
calibration has been performed to eliminate the systematic 
errors due to the camera's optics. 
The capturing of the images is done in full synchronization with 
the rotation and lighting of the laser beam device so that in a 
single cycle of the system the following steps are performed: 
Step 1) Rotation of the disk by a small angle (about 2°) 
Step 2) 1* Image capture (fig. 3a) 
Step 3) Switching on the laser beam 
Step 4) 2" Image capture (fig. 3b) 
Step 5) Switching off the laser beam 
The position (exterior orientation) of the camera during the 
image capturing, on an arbitrarily defined coordinate system is 
  
  
produced using well-defined target points located on the 
rotation disk (fig. 3). 
The difference between the 2 images taken in the 2™ and 4% 
steps of the cycle gives with great accuracy the imaged position 
of the points that describe the object. The calculation of these 
points is produced with the use of a photogrammetric process 
since the position (exterior orientation) and geometry (interior 
orientation) of the camera are already known. 
By repeating these steps the whole object is scanned, and a 
dense point cloud is created (fig. 4). The steps used to produce 
the calculated 3D points of the object may vary since the 
complexity and size of the object is also indeterminable and 
stochastic. The size of the rotation angle defines the spatial 
  
  
  
  
  
  
  
  
  
  
  
  
Fig. 4. Point cloud model presented in Bentley Systems Microstation 
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