# Influence of Headlight Level on Object Detection in Urban Traffic at Night
## 3 Results
### Photometric Results
In the next step, the Visibility Levels are calculated for the individual object positions in the various constellations (test road and vehicle position). Based on the contrast curves from Figures 6-8, this evaluation step is limited to the two boundary values, namely, low beam off and low beam fully switched on. The calculated Visibility Levels for test road 1 are shown in Table 2 (vehicle position 1) and Table 3 (vehicle position 2). Here, the information in the first row represents the distance in front of the vehicle and the information in the first column represents the position on the roadway, with 0.0 m representing the object positions on the longitudinal axis of the vehicle's centerline. A negative prefix means that the object was positioned to the left of this longitudinal axis and a positive prefix means that the object was positioned to the right of the longitudinal axis. It should be noted that the absolute value of the luminance difference is used to calculate the Visibility Level, which means that the Visibility Level is always positive regardless of the contrast polarity. \begin{table}
\begin{tabular}{c c c c c} \hline  & \multicolumn{4}{c}{Low Beam off} \\ \hline  & 30 m & 45 m & 55 m & 65 m \\ \hline \(-\)3.0 m & 33.70 & 24.91 & 17.23 & 13.44 \\ \(-\)1.5 m & 33.33 & 22.27 & 14.82 & 12.51 \\ 0.0 m & 35.18 & 24.03 & 14.01 & 10.96 \\ 1.5 m & 40.21 & 28.21 & 24.07 & 17.12 \\ \hline \multicolumn{4}{c}{Low Beam fully switched on} \\ \hline  & 30 m & 45 m & 55 m & 65 m \\ \hline \(-\)3.0 m & 31.87 & 4.00 & 4.03 & 2.92 \\ \(-\)1.5 m & 88.68 & 10.34 & 0.06 & 4.78 \\ 0.0 m & 81.46 & 6.12 & 2.85 & 0.91 \\ 1.5 m & 33.19 & 4.09 & 12.06 & 9.56 \\ \hline \end{tabular}
\end{table} 
Table 2: Calculated Visibility Levels for test road 1, vehicle position 1. \begin{table}
\begin{tabular}{c c c c c} \hline  & \multicolumn{4}{c}{Low Beam off} \\ \hline  & 20 m & 35 m & 45 m & 55 m \\ \hline \(-\)3.0 m & 40.16 & 33.11 & 23.38 & 17.99 \\ \(-\)1.5 m & 39.45 & 28.68 & 20.92 & 15.63 \\ 0.0 m & 42.21 & 31.14 & 21.17 & 15.88 \\ 1.5 m & 48.19 & 33.76 & 31.38 & 21.35 \\ \hline \multicolumn{4}{c}{Low Beam fully switched on} \\ \hline  & 20 m & 35 m & 45 m & 55 m \\ \hline \(-\)3.0 m & 31.35 & 16.58 & 6.66 & 5.03 \\ \(-\)1.5 m & 149.04 & 34.15 & 17.31 & 4.95 \\ 0.0 m & 169.81 & 38.78 & 25.40 & 9.17 \\ 1.5 m & 54.34 & 20.08 & 2.54 & 0.57 \\ \hline \end{tabular}
\end{table} 
Table 3: Calculated Visibility Levels for test road 1, vehicle position 2. As shown in Tables 2 and 3, when the low beam is off, the existing street lighting produces a higher Visibility Level at all object positions for both vehicle positions than the Visibility Level of 7 for object detection determined in previous studies [52; 54]. The Visibility Level for vehicle position 1 ranges from 10.96 to 40.21, and for vehicle position 2 from 15.63 to 48.19. If the Visibility Level is now considered with the low beam fully switched on, it is noticeable that the maximum Visibility Level increases significantly. The maximum Visibility Level for vehicle position 1 is 88.68 and for vehicle position 2 it is 169.81. This means that the low beam at these positions is excessive for detecting the objects, as it is larger by a factor of about 12 to 24 compared to the Visibility Level of 7 determined in previous studies [52; 54]. On the other hand, the minimum Visibility Level with fully switched on low beam is so low, with 0.06 for vehicle position 1 and 0.57 for vehicle position 2, that the luminance difference between object and background is lower than the threshold luminance difference according to [PERSON]'s Small Target Visibility Model [30]; thus, detection of these objects is definitely no longer possible. In addition, the Visibility Level on 9 of 16 positions for vehicle position 1 and on 5 of 16 positions for vehicle position 2 is below the Visibility Level of 7 determined in previous studies [52; 54], which indicates more severe detection conditions.