0  road                                          
1  sidewalk                 
2  building                 
3  wall 
4  fence                    
5  pole                 
6  traffic light  
7  traffic sign                 
8  vegetation                   
9  terrain
10  sky                 
11  person                  
12  rider
13  car                 
14  truck                   
15  bus
16  train                   
17  motorcycle                  
18  bicycle                 