Daylight vision

Figure 6.18 Spectral degree of sensitivity to brightness (daylight vision) and V ( ) (night vision) (according to DIN 5031, P. 3).

Hence, the entire human eye can be understood as an optical system with adjustable focal length (16.5-125 mm) and aperture (2-8 mm) [4]. The mean values for standard daylight vision are an aperture of 4, 6 mm and a focal length of 24 mm [5]. These optical values may be used to emulate the properties of the human eye for artificial depth-of-field renderings (see Chap. 15, Sect. 2). 

Color-order systems, such as the many MunseU collections available from Macbeth, have been described previously. Essential for visual color matching is a color-matching booth. A typical one, such as the Macbeth Spectrahte, may have available a filtered 7500 K incandescent source equivalent to north-sky daylight, 2300 K incandescent illumination as horizon sunlight, a cool-white fluorescent lamp at 4150 K, and an ultraviolet lamp. By using the various illuminants, singly or in combination, the effects of metamerism and fluorescence can readily be demonstrated and measured. Every user should be checked for color vision deficiencies. 

The CIELAB system (1976) strictly standardizes the light source and the observer. CIE recommends three standard sources, A is an incandescent lamp, and B and C are lamps provided with different two-cell Davis-Gibson liquid hlters that simulate noon daylight and average daylight, respectively. Since the main object of the system is to obtain colorimetric results for normal tri-chromats (people with normal color vision), the standard observer must represent the human population with normal... 

Optical detectors shall be used in more open configurations where ressure buildup due to the incipient explosion is limited. Optical etectors shall not be used where high dust concentrations limit the reliability of the suppression system. Both uv and ir detectors are available for optical detection. The use of daylight-sensitive sensors shall be avoided to avoid spurious activation. The sensor shall be mounted such that the angle of vision allows it to cover all the protected hazard area. The performance of an optical detector will also be affected by any obstacles within its vision, and this shall be overcome by the introduction of more detectors. Optical detectors shall be fitted with air shields to keep the optical lens clean. 

Vision results from signals transmitted to the brain by about 125 million sensors located in the retina. These photoreceptors are of two types, called cones and rods. Cones work under intense light - that is, during daylight hours - and this mode of vision is called photopic vision. Rods work under dim lighting conditions, and this is called scotopic vision. 

For all these reasons, iron will always maintain a modest presence and we are saved from the terrifying vision of a completely metallic Universe. So, dear Aristotle, we no longer stand before the evidence like bats in daylight. 

Note the equation of an extremely stimulated imagination with a dreamlike state. From the facts that he found the daylight to be unpleasantly glaring and the corresponding release of an uninterrupted stream of fantastic pictures, we can safely conclude that Hofmann s LSD visions were produced by a dreamlike shift in the chemical balance of his visual brain. And, indeed, Hofmann himself offered the hypothesis that the stimulating effects on his visual brain were caused by LSD s interference with serotonin, the brain modulator that later physiological studies showed to be radically reduced in REM sleep. 

Figure 41.10. Left The first low energy Supermarket Tengehnann Klimamarkt in Muhlheim an der Ruhr, Germany, with an 82 m OKAGEL day-lighting system in the roof. Right Vision from the inside showing the function of the daylighting system.

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