c Influences the thinking of how to handle 
precision. The calibration procedures might have 
looked different. 
d Nothing special in the data extraction part. The 
bundle adjustment using known distances in the 
system calibration and the 3D calculations. 
e The high precision of the system is made possible 
because of the high resolution cameras and the 
distinct targets. The precision is verified against a 
known reference, while the error theory is of 
minor interest. The reliability is in one sense 
limited since only two cameras are used. The 
special light pen works as an indicator if 
something is wrong with measurements or c 
ameras. There are no ways of automatically 
correcting errors during the measuring phase. 
Technical Description 
Two Videk Megaplus CCD-cameras (7 frames/sec) 
System orientation with known distances 
Measures on laser spots or LED's 
33 points/sec 
The measuring uncertainty is described as 0.05 + 
L/10000 (mm) 
VME motorola 68030 for image processing tasks. HP 
workstation in Unix environment for operator 
Special details: 
Light pen for inaccessable points 
Connections to various CAD-systems 
Tip Selector Button 
Indicator LEDs 
  
  
  
  
Exposure Butto! 
Twist Levei 
Fig9 Light Pen 
52 System2 MacReflex, Qualisys AB@® 
a A new system with three goals 
- Simple to use 
- High technical performance 
- Reasonable price 
b Background in electrical engineering 
c Did not know, but emphasized the need of 
competence in industrial development and 
manufacturing 
   
  
   
    
   
   
   
   
    
   
    
   
   
  
  
   
  
   
    
   
   
  
  
   
   
   
  
   
  
    
   
  
  
   
  
   
   
   
   
   
    
     
  
d Nothing special in the data extraction part. Uses a 
DLT solution for the orientations, which they 
became familiar with during earlier work with the 
SELSPOT system. 
e The high internal precision of the system is made 
possible because of the distinct targets and a special 
hardware unit for each camera. This also enables 
the very high sampling frequency, 20 points/50 Hz 
frame with up to 7 cameras. The external precision 
and reliability is partly due to the simple 
orientation procedure with a DLT using five points 
and one point for control. There are no automatic 
self-diagnostic in the system. 
Technical Description 
2 - 7 CCD cameras with dedicated hard-ware 
System orientation with calibration frame, DLT 
Measures on reflective targets 
20 points/frame at 50 Hz, The different cameras may 
be connected in muktiplex mode to raise the image 
acquisition rate. 
The absolute accuracy 0.04 % 
Developed for the Macintosh environment 
Special details: 
Easy to use for operator 
Very fast measurements of image coordinates 
Ed Up to 7 
E. iei | Cameras 
T A == | possible 
Additional for 3D system 
ce XY 
coordinates 
Monitor Camera Video processor Macintosh 
  
   
   
  
  
  
  
  
  
Fig 10 MacReflex System Configuration 
5.4 System 3 Mapvision, Oy Mapvision ltd [1 
a Defined goals in 1977 which now are fulfilled 
b Mixed background of surveyors and electronical 
engineers. 
c The design of the system would have looked 
different if only one of the groups had been 
present, e.g. the calibration procedures. 
d Utilizes the full information of the grey-level 
image to achieve high precision and measures one 
point at the time, which reduces the 
correspondence problem. The calibration is done as 
a bundle adjustment with self-calibration using 
known distances. This makes it easy to have a high 
number of points in the calibration phase.