Abstract
Dunbar's values of the luminance difference threshold under street lighting conditions are confirmed by new measurements showing the influence of motion of the object, exposure time and probability of recognition. The visibility of the standard test object under dynamic conditions and under the influence of disability glare is derived, leading to the revealing power. There is evidence that the limitation of disability glare must not be defined using a single visual function, but should be related to the value of revealing power. The statistical treatment of the revealing power of large composite objects such as pedestrians leads to reasonable values of revealing power. It is proposed to use this single figure as a figure of merit for appraising the quality of a street lighting installation taking into account the individual physiological aspects of average luminance level, luminance distribution, disability glare and contrast rendering.
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