## 2 German Traffic Space Analysis
### Traffic Space Distributions  
Since all drives and therefore the traffic discussed here were recorded during night, only two major groups of objects were relevant: motor vehicles and traffic signs. Overall the object distributions were as expected. As an example for a typical traffic sign distribution, Figure 4 shows the country road distribution.  
Here, it is obvious that most traffic signs that are being approached on country roads are located along the right side of the road. They are first recognized by the camera and algorithm within a certain distance at around \(2^{\circ}\) vertically and at around \(2^{\circ}\) horizontally. As soon as the vehicle comes closer to the traffic sign, the sign moves toward the top right corner of the camera's field of view--a normal geometric behavior.  
On motorways, this looks fairly similar, but a significant portion of traffic signs is also found above the road with a small proportion also being registered to the left of the road. However, this highly depends on the lane the vehicle is in, as usually a traffic sign that is placed on either side is duplicated on the other side as well. Therefore, the traffic sign distribution is much less pronounced and blurrier.  
In cities, traffic signs appear mostly on the right side again, but are placed at much greater vertical variance, blurring the distribution image as well.  
When it comes to motor vehicles, the distributions are easily explained. On country roads, the traffic is mostly recognized to the left of the vehicle and directly in front. In the city, due to parked vehicles and the relatively low relative velocity to other vehicles, objects can be recognized almost anywhere in front of the driver's vehicle.  
Figure 4: Density distribution of traffic signs on country roads from dark blue (no traffic signs) to bright yellow (normalized maximum number of traffic signs found).  
Figure 3: Histogram of the calculated road curvatures for urban roads (blue), country roads (light red), and motorways (yellow).  
Motor vehicles seem to be the most interesting here. Since the relative velocity to passing vehicles is rather low as well, and similar on the left and right, two major \"hot spots\" on each side exist. This is shown in Figure 5.  
Overall the data show that most objects are found on motorways and in cities. Figure 6 shows the relative number of frames with at least one motor vehicle (orange, dotted line) or one traffic sign (red, solid line) for the three road categories, as well as overall.  
A total of 230,000 cars, 9500 trucks, 400 buses, 20 motorbikes and 150,000 traffic signs were recognized and evaluated by the software. It should be noted that this does not mean that 230,000 different cars were recognized nor that there were 230,000 frames with cars. A single car can appear on multiple frames and therefore be counted multiple times into this statistic. At the same time, it is also possible that multiple cars are on one frame and therefore, both count into this statistic as well.  
While these data bring no real surprises, it is absolutely necessary to have valid real-life data for the next steps in the light distribution optimization.