Models for Spectral Luminous Efficiency in Peripheralvision: Performance Based Evaluation of Visibility at Lowluminance Levels

Visibility calculations for night-time conditions arecurrently based on day-time vision. Under reducedlight levels, such as road lighting, the spectralsensitivity of the eye is, however, different inperipheral vision. Peripheral vision, which includesmajor part of the vision, plays important role insituations where presence and motion of objectsoutside the central vision affect the safety andjudgement of actions. Currently applied models basedon central vision lack the ability to describe visualperformance in peripheral vision correctly. In thisbook, two different performance based methods wereapplied to evaluate the spectral sensitivity of theeye. Results reveal that spectral sensitivity of theperipheral vision should be described with its ownmodel. A candidate model for this purpose ispresented. Furthermore, a model for spectralsensitivity as a function of luminance level atmesopic and low photopic luminance levels ispresented as well. These models give information onthe visual performance of the human eye at low lightlevels. This knowledge is useful to professionals inthe fields of lighting and vision.