CMRT09: Object Extraction for 3D City Models, Road Databases and Traffic Monitoring - Concepts, Algorithms, and Evaluation 
(b) Virtual view of the input 3D model 
(c) Result of the camera selection by 2D ray-tracing: 
no camera was detected for the current wall 
(d) Result of the camera selection by 3D ray-tracing: 
8 cameras were found viewing the current wall. 
Figure 11. Example of a low building masking a façade 
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