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Anyone who has worked underwater can give many reasons for taking pichres. The photograph provides the user with a high resolution, permanent record for later study and evaluation. The photographic camera is an essential tool for anyone working underwater who needs to gather and record high resolution visual information.© (1971) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

At night, car driving requires as much - or perhaps even more - visual information as driving during day-time. The fact that generally speaking the night-time accident rates are some three times as high as the corresponding day-time rates must be at least partially contributed to the lack of visual information at night (swot/ 1969), more likely so if the fact is taken into account that on roads with good overhead street lighting the accidents are some 30% lower than on unlit or poorly lit roads, where car-drivers have to rely on their headlamps (OECD 1971, Box 1971, Cornwell and Mackay 1972). With present-day technology, driving a car involves the driver as an active element, and it can be done only when a large amount of visual information is presented. Details regarding the driving task may be found elsewhere (Anon 1971, Asmussen 1972), together with details regarding the role therein of transport lighting (Schreuder 1970a, 1971). For the present discussion, however, it is enough to summarize this task in two sub-tasks: primo following the road and secundo avoiding obstacles. As indicated, at day and with good overhead lighting these sub-tasks can be performed reasonably well; major problems, however, arise when vehicles have to proceed on unlit roads. They can be related to the general lighting requirements that can be described as: sufficient high and uniform road luminance, glare restriction, and visual guidance (Schreuder 1970b).