# Influence of Headlight Level on Object Detection in Urban Traffic at Night
## 1 Introduction
Thus, the influence of vehicle illumination is reduced as the illumination level on the road increases [53]. [PERSON] et al. conducted a study to determine the required Visibility Level for the detection of 0.2 \(\times\) 0.2 m objects with different reflectance levels (0.20, 0.30, 0.40, 0.50). For this purpose, images of an illuminated street with different illumination classes (M2, M3, M4, M5) and color temperatures (4000 K and 6000 K) were presented to 30 test subjects. The results of the study showed that a Visibility Level in the range of 7.0 to 8.5 is required in order for objects to be detected with 100 % probability. Furthermore, no influence of the light spectrum on the detection was found [54]. [PERSON] et al. studied the effect of vehicle illumination on the detectability of objects at different distances on illuminated roads. They found that there is a change in contrast polarity (positive to negative contrast and vice versa) depending on the distance in front of the vehicle. In addition, objects with negative contrast were detected at greater distances than objects with positive contrast. Furthermore, the relationship between pedestrian contrast and visibility was complex, as pedestrians showed both positive and negative contrast [35; 55]. In laboratory and field studies, [PERSON] showed that due to the high scenario complexity in the urban area, higher contrasts are needed for the detection of objects. Furthermore, he found negative contrast results in contrast sensitivities that were up to 30% higher than those using positive contrast [13]. Studies by [PERSON] et al. [56] and [PERSON] et al. [57] showed that the detection distance increases with increasing street lighting intensity. In addition, they concluded from their studies that the effect of the low beam on the detection conditions is high at short distances and decreases with increasing distance until no effect in nighttime urban traffic can be observed from a distance of about 80 m [56; 57]. [PERSON] et al. performed photometric studies in which they calculated the Visibility Level under different light distribution ranges for different illumination classes from M3 to M6. They found that the required light distribution range depends on both the illumination class and the reflectance of the detection targets [61]. In considering subjective safety parameters, [PERSON] et al. found that, for a safe driving experience and detection of objects on illuminated roads, a dimmed version of the low beam can be used rather than the full intensity of the low beam, thereby reducing the energy demand of this function [58; 59; 60]. The studies conducted thus far show that the detection conditions in urban nighttime traffic environments depend on both street lighting and vehicle illumination. The respective effect depends mainly on the distance between the object and the vehicle. According to [PERSON] et al. [62; 63; 64], vehicle illumination is mainly responsible for detection conditions at close range, while street lighting dominates at long range. In the intermediate range, however, both lighting systems have an influence on the prevailing detection conditions. In contrast to the majority of the considered studies, [PERSON] et al. suggest designing intelligent street lighting systems and increasing their intensity. According to [PERSON] et al., taking into account previously known results on the negative mutual influence of motor vehicle and street lighting [35; 57; 55; 52; 53], street lighting should be reduced in the presence of motor vehicle lighting in order to achieve the necessary detection conditions on the one hand and to strive for energy-efficient use on the other [62; 63; 64]. The following research questions arise from the previous research, and are answered in this paper:  
1. What is the influence of different road illumination levels and luminous intensities of motor vehicle headlights on the detection of objects at different distances and angular positions in front of the vehicle? 2.