Visual Performance Under Mesopic Conditions: Towards Determination of Adaptation Luminance

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Volume Title
School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2015-11-13
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Date
2015
Major/Subject
Mcode
Degree programme
Language
en
Pages
56 + app. 92
Series
Aalto University publication series DOCTORAL DISSERTATIONS, 163/2015
Abstract
The Commission Internationale de l'Eclairage (CIE) published a system for visual performance-based mesopic photometry in 2010. It is valid between the luminances 0.005 cd/m2 and 5 cd/m2. In night-time driving conditions, the luminances in the visual scene are in the mesopic range; thus, mesopic photometry should be adopted when assessing lighting in outdoor areas and other night-time traffic environments. In order to implement the CIE mesopic photometry, the background photopic luminance, i.e. adaptation luminance, is required as an input value. The aim of the study is to develop methods for estimating the field of view of which the luminance is to be used as the adaptation luminance in implementing the CIE 191 system for mesopic photometry. This is realised by applying methods such as combining eye-tracking data with corresponding luminance data and analysing peripheral target detection under uniform and non-uniform luminous backgrounds. In the study of combining eye-tracking measurements with luminance data, the visual scene areas with the highest density of gaze distributions were determined. The measured luminances for these visual scenes were used to form an estimate of the adaptation luminance under different driving conditions in the lit and the unlit sections of a rural road. The mean luminances of the estimated fields were higher in the unlit section than in the lit section of the route for all drivers. This was due to high-beam head-lights that illuminated the road surface, whereas the gaze points were concentrated in the unlit section. Experiments in laboratory conditions were conducted in order to obtain the effect of background and target location and its luminance on visual performance. Reaction time and contrast threshold measurements were made to analyse peripheral target detection in uniform and non-uniform backgrounds. Under non-uniform background luminances, peripheral target detection depends on the local luminance of the target and the luminance uniformity of the surrounding area of the target. The results verify that each part of the retina adjusts its sensitivity independently, which refers to local adaptation. However, the complexity of the visual field also has an effect on visual sensitivity in peripheral vision. Further studies, where road type, driving speed and discomforting glare are taken into account, are needed to define the visual adaptation field and corresponding adaptation luminance in various driving conditions.
Description
Supervising professor
Halonen, Liisa, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland
Thesis advisor
Puolakka, Marjukka, Dr., Aalto University, Department of Electrical Engineering and Automation, Finland
Keywords
mesopic vision, visual adaptation, eye-tracking, reaction time, contrast threshold
Other note
Parts
  • [Publication 1]: I.Puolakka, Marjukka; Cengiz, Can; Luo, Wei; Halonen Liisa. ‘Implementation of CIE 191 Mesopic Photometry – Ongoing and Future Actions’. Proceedings of CIE Lighting Quality & Energy Efficiency, 2012, Hangzhou, September 24–26, p. 64–70.
  • [Publication 2]: II. Cengiz, Can; Kotkanen, Henri; Puolakka, Marjukka; Lappi, Otto; Lehtonen, Esko; Halonen, Liisa; Summala, Heikki. ‘Combined eye-tracking and luminance measurements when driving on a rural road: towards determining mesopic adaptation luminance when driving’. SAGE Journals. Lighting Research and Technology, 2014, volume 46, issue 4, pp. 676–694.
    DOI: 10.1177/1477153513503361. View at publisher
  • [Publication 3]: III. Cengiz, Can; Puolakka, Marjukka; Halonen, Liisa. ‘Reaction time measurements under mesopic light levels’. Proceedings of CIE Lighting Quality & Energy Efficiency, Kuala Lumpur, April 24–26, 2014, pp. 532–537.
  • [Publication 4]: IV. Cengiz, Can; Puolakka, Marjukka; Halonen, Liisa. ‘Reaction time measurements under mesopic light levels: Towards estimation of the visual adaptation field’. Accepted for publication in the journal Lighting Research and Technology in the year 2014. Published online before print October 20, 2014.
    DOI: 10.1177/1477153514554494 View at publisher
  • [Publication 5]: V. Cengiz, Can; Maksimainen, Mikko; Puolakka, Marjukka: Halonen, Liisa. ‘Contrast threshold measurements of peripheral targets in nighttime driving images’. Accepted for publication in the journal Lighting Research and Technology in the year 2015. Published online before print March 26, 2015.
    DOI: 10.1177/1477153515578308 View at publisher
  • [Publication 6]: VI. Cengiz, Can; Maksimainen, Mikko; Puolakka, Marjukka: Halonen, Liisa. ‘Effects of high luminance objects on peripheral target detection in night-time driving images’. Submitted to the journal Light and Engineering on 18 December 2014.
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