Blinded by the Light, 2020

(1) Disability Glare is the reduction in visibility caused by intense light sources in the field of view. Discomfort Glare is the sensation of annoyance or even pain induced by overly bright sources (Rea 2000).

(2) The word brightness is commonly used but is technically incorrect. It is luminance and is measured in candelas/square metre.

(3) There are considered three different vision regimes. Photopic vision relates to human vision at high ambient light levels (e.g. daylight) and applies to luminance levels > 3 cd/m2. Scotopic vision relates to human vision at low ambient light levels (e.g. night) but the sense of colour is largely lost – seeing a range of gray light, and applies to luminance levels < 0.003 cd/m2. Mesopic vision relates to light levels between the photopic and scotopic visions.

(4) The artist James Turrell exploits this fact in most of his work on the limits of visual perception.

(5) ‘Reflectivity: dealing with rogue solar reflections’ by David N.H. Hassall, 1991, Building Research Centre, School of Building, University of New South Wales.

© 2020 Ian Ritchie