Application Threshold Brightness Contrast Experiments of Human Eyes for Study on the Visibility
The primary purpose of road lighting at night is to provide for drivers and pedestrians with good visibility, and reach the purposes of safe, comfortable, speedy operation and beautifying the environment. This paper studies visibility of road lighting, analyzes the influence factors of the visibility; conducts experiments on threshold brightness contrast of the human eyes, suggests the K value in the visibility calculation suitable for the experimental data; researches the small target visibility calculation model, and simplifies it.This article analyses the influence factors of visibility and development process of visibility design, points out the main factors of influencing the visibility level, such as the target brightness, the immediate background brightness, environment brightness level and disfunctional glare. Moreover, it is the amendment of the duration of a target, the age of observer and negative contrast (the brightness of targets is smaller than that of background) that have a certain impact on the visibility. And the use of small target visibility methods for road lighting design is direct and effective, and there is great potential for energy conservation and saving costs. Furthermore it is a new method in traffic safety and saving the use of energy.This paper develops the threshold brightness contrast experiments of human eyes, and determines the important factor K in the visibility calculation models. This paper simulates the threshold brightness contrast experiments of American scholars Blackwell through computer program, obtains the threshold brightness contrast data in the positive and negative contrast conditions, different identification probability, brightness different backgrounds and different perspectives through regression analysis and fits out the relationship between the identification probability with relative comparison. It can be found through the threshold contrast data analysis in the positive and negative contrast conditions that the brightness contrast C is high with the increase of the identification of probability; low with the increase of the perspective and low with the increase of background brightness in uniform conditions. The negative brightness contrast C is significantly less than the positive, which shows that the ability of seeing dark targets in bright background is stronger than that of seeing bright targets in dark background. It is determined that the important constant K in the visibility calculation through the relationship between identification probability and the relative contrast, and according to the formula which is fitted out by the experimental data of the 20 observers, K equals 2.33 when identification probability P equals 99.96％.
Visibility Small target visibility Threshold contrast of human eyes Road lighting
Zhang Shengpeng Chen Zhonglin Weng Ji Liu Bo Hu Yingkui Huang Ke Liu Yingying
Faculty of Architecture and Urban Planning of Chongqing University, Chongqing China 400045
国际会议
26th Session of the CIE(国际照明委员会（CIE）第26届大会)
北京
英文
92-95
2007-07-04（万方平台首次上网日期，不代表论文的发表时间）