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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
Figure 4: Traffic measurements using the proposed likelihood ratio detector for DT1516 
tected vehicles at their displaced positions are marked with red 
rectangles. The triangels are the positions of these vehicles back- 
projected to the assigned road. These triangles are color-coded 
regarding their estimated velocity and the range is from red to 
green, standing for 0 to 150 km/h. Having these detections pro 
jected back onto the road axis, it is possible to derive parameters 
for the situation on the road and using them for example for traffic 
models, see e.g. (Suchandt et al., 2006b). 
During the flight, video recordings of the traffic situation have 
been taken as reference information. The received velocities of 
this ground truth data represent the true traffic flow. The velocity 
distribution of the reference data corresponds to the one received 
from the detection results using DT01516 in Fig. 4. Most iden 
tified targets are trucks, hence the average of about 80 km/h is 
reasonable. 
5 CONCLUSION 
Traffic parameter estimation using TerraSAR-X data is possible 
with the proposed likelihood ratio detector. It considers simul 
taneously the effects due to the vehicle’s across-track and along- 
track motion. The results showed the potential to deliver informa 
tion from space about the traffic situation on roads for large areas. 
The derived traffic flow parameters from the detection in the SAR 
images show a good correspondance with those received from 
reference data. Integrating multi-temporal data helps to eliminate 
such wrong detections like shown and improve the reliability of 
the results. 
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