1400 [— 
1200 
1000 
800 | 
600 | 
Number of particles 
400 
200 
   
bidirectional) 
E Unlinked 38 
Linked 1388 
  
Figure 10: Results of the tracking methods (vortex simulation) 
8. CONCLUSIONS 
The paper gives an overview about the principles of 3D PTV 
regarding hardware solution, system calibration and data 
acquisition. The new spatio-temporal matching method 
developed at ETH Zurich is described. The actual 
implementation was tested with simulated and real image 
sequences and its operability has been proved. 
The application of a purely object space based tracking method 
leads to a considerable lower number of established connections 
in combination with a higher error rate. In the case of 
ambiguities the reliable calculation of additional particle 
positions from unused detections is only possible if image space 
based information is used in combination with spatial 
prediction. Compared to the previous implementation the 
number of linked particles could be increased by up to 40 %. 
The method can be used for manifold measurement tasks in the 
hydrodynamic flow analysis. 
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