Discomfort glare is defined as glare that causes discomfort without necessarily impairing the vision of objects. Traditional glare metrics fail for non-uniform luminaires. As an alternative, visual discomfort is determined by a physiological model incorporating the centre­surround receptive field mechanism and the pupillary light reflex. The pupil area, controlled by the pupillary light reflex, regulates the retinal illuminance. A centre-surround receptive field, described by a difference of Gaussians, represents the visual signal. The centre excites the signal whereas the surround controls the inhibition. A forced choice paired comparison experiment involves 7 non-uniform rear projected stimuli with different spatial frequencies. Inspired by a promising coefficient of determination of 0.90, the model is a candidate to replace current glare metrics as UGR or VCP, especially when non­uniform luminaires are to be evaluated. 1. CIE, International Lighting Vocabulary. Vienna: CIE, 1987.
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• discomfort glare
• luminance map
• receptive fields