CCd Cameras 
  
  
  
  
Sensors 
3 | 
  
  
  
  
IA ASCE New Technology 
Rh. 2 
4 | 
M À 
Vehicles 
  
  
  
  
  
  
    
   
  
* Image Processing 
* Image Compression 
  
    
  
* Kinematic Modelling 
* Quality Control 
  
Figure 1: Multi-Sensor Integration in Close Range Application 
  
Tvpe of sensor 
Tvpe of information 
Characteristics 
  
    
CCD Cameras 
Descriptive/Geometric 
Image, geometric accuracy depends on sensor 
resolution 
  
  
Imaging Laser 
Descriptive/Geometric 
Image + Distance between the object and the sensor 
  
    
    
Laser Profiles. Laser Scanners 
Geometric 
Distance between the object and the sensor, scanning 
angle 
  
  
    
  
Impulse Radar 
Descriptive/Geometric 
Thickness of objects (mainly used for pavement 
structure voids) 
  
Ultra-sonic sensors 
    
  
Geometric 
Distance between the object and the sensor Road 
rutting measurements, and cross section profiles 
measurement 
  
  
   
   
GPS positioning and attitude | Geometric 
High accuracy position and medium accuracy attitude, 
  
  
  
    
  
  
  
determination global reference 
Inertial sensors Geometric Low-to-high accuracy relative position and attitude. 
Odometers Geometric Distances. 
  
  
  
    
  
     
    
   
   
   
    
   
   
  
processing. 
Real-time georeferencing is, in principle, possible because the 
interior orientation can bc donc bcforc thc run and the exterior 
orientation parameters can be computed in real time. However, it 
is not advisable in applications where frequent lock of loss to 
GPS satellites occurs. In those cases, real-time georeferencing 
will be much poorer in accuracy and reliability than post-mission 
Implied in the georeferencing process is the synchronization of 
the different data streams. The accuracy of georeferencing is 
776 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996 
Table 2 : Summary of close-range photogrammetry related sensors 
dependent on the accuracy with which this can be done. The 
synchronization accuracy needed is dependent on the required 
system performance and on the speed with which the survey 
vehicle moves. It is therefore much more critical for airborne 
applications than for marine and land vehicle applications. 
Fortunately, GPS provides a well-defined time signal to which 
the other sensors can be slaved. Still, the implementation of 
sensor synchronization is not a trivial process and should bc donc 
with care. Some details are given in a later chapter. 
    
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