With every new headlamp technology entering into series production, a new possibility appears that claims to improve visual performance during nighttime driving. To judge such technologies and to generate an objective advance in perception for car drivers, it is crucial to know how the human visual system works under night time driving conditions. In 2010 the TC 1-58 of the CIE published a first "Recommended System for visual performance based mesopic photometry" which is - among others - to be applied for driving a car by night. This CIE approach pictures a unified and simplified model of twilight visual performance. Of course this is a big step forward in photometry, but simplification prevents a deeper description of the visual processes taking place in the mesopic range and thus not giving the chance to optimize additional relevant quantities like "detection probability" or "feeling of safety". Visual mechanisms also working in the photopic range behave in a completely different manner when the state of adaptation becomes lower approaching night-time road lighting levels. Another drawback of the CIE model is that it is based only on experiments that took place under simplified laboratory conditions without considering inhomogeneous luminance distributions or age-related pupil size. Typical inhomogeneous luminance distributions are regulated in international standards for vehicle lighting. Laboratory test were performed to achieve a basic understanding about general methodology in brightness matches and the spectral sensitivity of the human brightness perception in the mesopic range. We can say that we use a bias free and optimal (in terms of the parameters above) procedure to generate stable and significant results. As a first outcome, we will present a mesopic brightness sensitivity function which will describe brightness perception be a lot more precise than V(X). From this initial point, first steps are made towards a spatially resolved mesopic brightness model for automotive purposes.
Brightness perception in the mesopic range - models and new laboratory experiments
Helligkeitsdurchdringung im Bereich der Dämmerung - Modelle und neue Laborexperimente
2011
8 Seiten, 15 Bilder, 4 Quellen
Conference paper
English
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