Photometric measurements for visibility level computations

A standard quality index in road lighting design is visibility level. In order to compute the visibility level of a target, three photometric values are needed: its luminance, the luminance of its near background and the adaptation luminance. The authors discuss the consequences of how these parameters are set on the ability to predict the performance of a driver at target detection. An experiment using a closed-road circuit was designed in which sixteen targets were presented twice to 34 subjects. Six visibility level assessment methods were compared. The background luminance was set as the luminance at the bottom of the target, as the mean luminance around the target, or as the luminance associated with the maximum target contrast. The adaptation luminance was set either to the background luminance or to the mean luminance. The best non-linear fit between computed visibility level and target detection performance was found using the maximum contrast over the four sides of the square target, and setting the adaptation luminance to a unique estimated road luminance instead of the local background luminance. The results of the experiment suggest that because of the variability of the visibility level data, great caution should be exercised when using it as an index of road visibility.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/14771535
• Authors:
  • Bremond, Roland
  • Dumont, E
  • Ledoux, V
  • Mayeur, A
• Publication Date: 2011-3-1

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 119-128
• Serial:
  • Lighting Research and Technology
  • Volume: 43
  • Issue Number: 1
  • Publisher: Sage Publications Limited
  • ISSN: 1477-1535
  • Serial URL: http://lrt.sagepub.com/

Subject/Index Terms

• TRT Terms: Contrast; Drivers; Experiments; Highway safety; Lighting; Lighting systems; Luminance; Photometry; Visibility
• Subject Areas: Highways; Safety and Human Factors; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 01342371
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 22 2011 7:58AM