Discomfort Glare from a Cyclic Source in Outdoor Lighting Conditions

Abstract

Many models of discomfort glare have been proposed for outdoor lighting applications. Most of them were built from data collected in the laboratory in static situations, with motionless light sources, which main characteristics (luminance, size and position) were constant over time. However, on the road at night, drivers are moving with multiple sources around them. To fill the gap between static situations and more realistic ones, four psychophysic experiments were carried out in a laboratory to investigate the impact of the cyclic variations of several light source characteristics (its luminance, eccentricity and solid angle) on the discomfort glare. The temporal frequencies have been chosen representative of outdoor lighting conditions, up to 2.6 Hz. No impact of the dynamics of the glare source was found, except for a source with variable luminance at a low frequency (f = 0.65 Hz).

Stimulus Range Effect in Discomfort Glare Studies

“…This is what Girard suggested, using simplified scenarios of the situations they were interested in (a driver seeing a series of luminaires, or a couple of vehicles headlamps) to choose the range of luminance, eccentricity, size, etc. of their stimuli [16]. From such real-life scenarios, and from a survey of the photometric properties of the corresponding glare sources, it seems possible to choose a range of stimuli close to what people experience in the target situation.…”

“…For instance, existing models of discomfort glare due to outdoor lighting use to consider uniform light sources standing on uniform backgrounds, in static settings. This may be considered as a useful trade-off to build a model, but cannot generalize to all situations, with heterogeneous light sources [12], complex background luminance, sometimes moving light sources [16] and moving gaze [17].…”