Discomfort glare from sources of nonuniform luminance

Existing models used to predict discomfort glare are based on studies using sources of uniform luminance. This paper presents research investigating the effect of nonuniform source luminance on discomfort glare and provides insight into extending models of discomfort glare to sources of nonuniform luminance. This study was performed using sine- and square-wave gradients as the nonuniform luminance stimuli. For each nonuniform stimulus, 12 subjects made paired comparisons using a series of uniform stimuli until an equivalently discomforting uniform stimulus was found. The results of this study suggest significant perceptual differences between uniform and non-uniform sources. The major variable affecting these differences is the position of the source in the field of view. Nonuniform stimuli are perceived as more discomforting than uniform sources when the observer is fixated on them and are perceived as less discomforting when they are in the periphery of sight The results suggest that existing models conservatively estimate discomfort glare from sources of nonuniform luminance for most applications.