Quantitative relations between discomfort glare evaluation and photometric quantities such as illuminance at the observer's eye, average luminance of the source area, average luminance of the effective area and effective glare luminance for white LED sources having a variety of spatial luminance distributions have been investigated. Effective glare luminance, which is the sum of luminances in the luminaire area divided by the effective area, explains the scaling results of all sources in the same way. In addition, a new equation modified from the Commission Internationale de l'É clairage Unified Glare Rating formula using the effective glare luminance showed a strong correlation with the scaling results. It is thus suggested that effective glare luminance is a useful index of discomfort glare for light sources having different spatial luminance distributions.
Constant hue loci for unique red, yellow, green, and blue and the loci of four binary balanced hues (e.g., equally reddish and yellowish) were measured at 10, 100, and 1000 Td for two observers. Wavelengths of the unique hues were not invariant from 10 to 1000 Td. In Judd's modification of the 1931 CIE chromaticity diagram, only the unique yellow loci at 10 and 1000 Td plotted as straight lines. The other constant hue loci were curved, and all the constant hue loci changed with retinal illuminance.
To provide the fundamental data for a color zone map, the color appearances of nearly unique hue stimuli presented over the entire visual field were qualitatively and quantitatively evaluated by hue and saturation judgments, blackness evaluation, and categorical color naming. The hue of red and green stimuli shifts toward a unique yellow, while that of yellow and blue does not change with an increase in eccentricity. The saturation of all the stimuli falls with an increase in the eccentricity in all directions. On the basis of the unique hue component, color zone maps for red, dark yellow, yellow, green, and blue stimuli are drawn. All the color zone maps extend over a wider region in the temporal and lower directions than in the nasal and upper directions of the visual field. The results are compared with the color zones of previous studies. The relationship between the color zones and the color categorization, as well as the underlying mechanisms of reduced saturation and hue shift, is discussed.
A simulation method to determine adaptation luminance is proposed for implementation of the CIE mesopic photometry system. The simulation takes four factors into account: luminance distribution, eye movement of observers, surrounding luminance effect and area of measurement. Each factor is modelled as a two-dimensional geometrical function. The method determines an adaptation luminance for the area of measurement through four calculation steps. The simulation method was applied to examples of luminance distributions of outdoor lit scenes and the results were compared with possible simple predictors of adaptation luminance. The comparisons suggest that the average luminance of the area of measurement can be considered as a good approximation in most of the cases. Exceptions are scenes for pedestrians in which there are many bright sources surrounding the area of measurement.
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