Surface Luminance Research Articles

Videography for sky luminance distribution measurement

Daylighting as a key element in quality assessment of the built environment has led to an increasing interest in its corollaries, and in its integration with artificial light sources in interiors. The use of daylighting requires a knowledge of the sky luminance distribution since work plane illuminances and interior surface luminances depend on this. In this paper the recommendations of the Commission Internationale de l'Eclairage regarding sky luminance distribution measurements are reported, along with a survey of measurement techniques used to date. There follows a detailed description of videography, considering the principal system components, and finally some considerations relating to its possible application in this area are discussed.

自動車運転者の安心感と路面輝度

自動車運転者の安心感と路面輝度

道路の路面輝度に関する一考察

道路の路面輝度に関する一考察

Non Uniform Increment of Surface Luminance of Fluorescent Lamp due to Reflected Light from Reflector

Non Uniform Increment of Surface Luminance of Fluorescent Lamp due to Reflected Light from Reflector

Change in Automobile Visibility at Dusk.

Determinants of automobile visibility include the factors peculiar to the vehicle, such as type of lamps, as well as external factors, such as change in surrounding brightness. At dawn and dusk, even if the lighting conditions caused by the vehicle’s lamps remain the same, automobile visibility can be expected to change in accordance with the change in surrounding brightness. For this study, perception experiments by observers have been used to understand how visibility changes during twilight hours in the case of passenger cars and a motorcycle. In the experiments, the visibility of a passenger car with all lamps turned off is taken as the standard mean. The experiments show that, (in the case of an automobile with lamps turned on) the tendency of visibility to improve as the surroundings become darker can be quantitatively confirmed as a function of road surface luminance. Moreover, as a result of simulating perception judgments of observers by taking account of the two factors (a factor determined by surrounding brightness and one determined by automobile lights), it is possible to obtain analysis results that are quite similar to those recorded through actual evaluation.

Shape-from-shading on a cloudy day

In the classical shape-from-shading model, surface luminance depends primarily on the unit surface normal. However, under diffuse lighting conditions, such as the sky on a cloudy day, luminance depends primarily on the amount of sky that is visible from each surface element, with surface normal of secondary importance. This claim is formalized in terms of a dominating sky principle and a surface aperture function. An approximately functional constraint between surface luminance and aperture emerges. It is shown how to use this constraint to recover a depth map from an image efficiently. A curious difference from the classical shape-from-shading problem is uncovered. When one assumes a point light source, the local geometric constraints of the shape-from-shading problem lie along the surface. However, in the diffuse-lighting problem, the local geometric constraints are found in a visibility field, which is defined in the free space above the surface.

Drivers' headlight use: A lighting factoid

The relationship between the horizontal illuminance on the road and the number of vehicles using headlights is quantified for five different sites in upper New York State. The horizontal illuminance at which 50% of vehicles are using their headlights is significantly different for clear and cloudy sky conditions and for the different sites. The resulting road surface luminances at which 50% of vehicles have their headlights on are, for all sites and sky conditions, much higher than similar measurements carried out in the Netherlands in 1958. (A)

Psychological preferences for industrial lighting

Traditional industrial luminaires possess little if any uplight component. As a result, ceiling surface luminances and in some cases wall luminances in industrial settings tend to be low, giving the overall environment a cave-like appearance. Although this type of lighting can provide the required quantity of light on the work surface, it does little to address other design issues including the psychological needs of the industrial worker. Can room surface brightnesses in an industrial environment affect an industrial worker's visual perception and sense of satisfaction with that environment? This study compared four commercially available industrial lighting systems, each with a different percentage of uplight. Actual industrial workers from various companies evaluated the systems in an industrial-like setting. Both a semantic differential scaling technique and a lighting-specific evaluation technique were used in the study. The results indicate a preference on the part of industrial workers for an environment with higher average room surface luminances. Impressions of spaciousness, brightness and stimulation correlated with an overall preference for higher surface luminances. The implication is that the psychological impact of lighting in the industrial environment should be an important consideration during the design process for industrial spaces.

トンネル内煤煙透過率と所要路面輝度

トンネル内煤煙透過率と所要路面輝度

A Measurement and Data Processing System for Car-following Behavior Analysis

This paper deals with a system which continuously measures speed, acceleration, and following distance of cars running on actual roads, and which processes the data measured. This system has been developed in order to analyze car-following behavior empirically. The functional merits of this system are (1) to observe car-following behavior precisely and continuously even in tunnels and (2) to measure road surface luminance, accelerator pedal displacement together with the car-following behavior itself. Kaiman smoothing algorithm is employed to process the car-following data based on the physical relationships among acceleration, speed, and following distance in order to reduce measurement errors, to correct for measurement bias, and to compensate for the momentary lack of following distance measurements. This system was tested on expressways.

Effect of Haze on Luminance

AbstractThe results from measurement, at a distance, of surface luminance, as it is affected by an intervening atmospheric haze, have been published. These show a large effect of quite small distances upon the readings. The present paper gives an analytical description of this behaviour which confirms the form of the measured variation of luminance.

Visibility research for road lighting based on a dynamic situation

Much of visibility research related to road lighting is based on static tests with small objects. At an open-air road lighting laboratory a series of dynamic tests have been conducted. For this purpose a normal motor car was equipped with a measuring and recording set-up. The 'objects' to be detected by the drivers of this car were pedestrians. These pedestrians were not on the carriageway, but on the adjacent surroundings of the road. The results of these tests confirm the importance of the average road surface luminance. The improvement in visual performance is found to be considerable up to a lighting level of 3.4 cd/m2. Concentrating the light on the carriageway has a negative effect on visual performance as far as pedestrians positioned outside the carriageway itself are concerned: at least 40 per cent of the average illuminance on the traffic lane must be available on the adjacent surrounds.

Mapping sky and surface luminance distribution using a flux mapper

A prototype, all-sky flux mapper has been developed at the Solar Energy Research Institute (SERI). The flux mapper is a video system which provides a rapid, real time processing of daylightning luminance data. The system uses an orthographic-projection fish-eye lens to project the entire image of a 180° field onto a vidicon target. The signal is then digitized and may be plotted as equal brightness comtours or recorded on tape for later analysis. The system has great potential for use in delineating illuminance distribution of the sky and of interior spaces.

Road lighting-as calculated and as in service

Extensive measurements have been made of the lighting qualities on about 100 main roads in Britain. Results have been collected for average road surface luminance, illuminance and uniformity, for surrounding luminance, disability and discomfort glare, and for the road surface characteristics. The degree of variation of road surface luminance along the road has also been noted. As such, this constitutes a large body of data on the quality of British lighting today. This paper then compares measured with calculated values of road luminance. Indications are given regarding the effectiveness with which installation performance can be predicted.

Full scale driving experiments - Uniformity and perception under road lighting conditions.

Ensuring perceptual conditions that the driver is to be able to detect a critical object ahead, at a sufficient distance, to take necessary driving manoeuvres safely, an attempt was made to find the admissible limit of the uniformity of the road surface luminance (U=Lmin/Lr) in relation to the average road surface luminance (Lr), under full scale road lighting installations with actual driving. (Lmin is the luminance of the darkest part of the road surface.) In the experiments, in total, 56 different combinations of U and Lr were provided and observed. Applying a forced choice method, correct responses of the observers in the car driven at a constant speed of 60 km/h, concerning the lateral positions of object(s) located against the darkest part of the road surface, presented in a random ordar, were collected and analyzed for each combination of U and Lr. Based on the data collected, probabilities of the correct perception of (lateral position of) the critical object were derived. Finally, the admissible limit of U is given as a function of Lr, to perceive the object with a probability of 75%, taking the luminance contrast of the object as a parameter. Consequently, it has been found that the square of the admissible limit of uniformity varies in proportion to a ratio between Lu and Lr, i.e. U2=Lu/Lr, where Lu is the luminance of the road surface necessary to perceive the object when U=1.0. The relation given agrees well with that obtained with the lighting simulator, and those derived from the results of previous researchers.

Bases physiques de la télédétection et sa problématique

(1978). Basic physical principales and problematical aspects of teledetection. La Houille Blanche: Vol. 64, No. 7-8, pp. 491-499.

The luminance of road surfaces during twilight : Krochmann, J., Ozver, Z. and Stockmar, A. (In German) Lichttechnik, Jul 1974, 26. 318–319 and Aug 1974, 26, 347–349; abstr in Lighting and Research Technology

The luminance of road surfaces during twilight : Krochmann, J., Ozver, Z. and Stockmar, A. (In German) Lichttechnik, Jul 1974, 26. 318–319 and Aug 1974, 26, 347–349; abstr in Lighting and Research Technology

Polarization of light reflected from rough planetary surface

A calculation is made of the luminance and polarization of light due to single and double reflections from the faces of particles in a surface composed of random, irregular particles using equations of electromagnetic waves and materials with a complex index of refraction. Some geometric properties of shadows are derived and used. Good agreement is obtained between these results and measurements of polarized light from Mars, Mercury, and the moon, including the phenomenon of negative polarization at small phase angles. Negative polarization is found to be caused by shade and shadows affecting the double-reflected rays. Graphical results are provided for materials of varied real and complex indices of refraction. The model can be used to calculate polarization and luminance of rough astronomical bodies and surfaces as a function of the viewing angle. Calculated ratios of single-reflected, double-reflected, and randomly diffused light can be related to the surface structure and optical properties of the material.

European Approach to the Luminance Aspect of Roadway Lighting

In both interior and public lighting, the ultimate aim of lighting design is to create a luminance pattern in the visual field that meets the requirements of visual performance, visual comfort, and economy. Roadway lighting design can be based on requirements for roadway surface luminance since the road surface occupies the main part of the visual field. In the last 20 years, European countries have attempted to solve luminance design problems in a way suitable for practical application. This period of research appears to be ending. Meanwhile, the luminance method of roadway lighting, as described in this paper, is becoming increasingly popular in European countries.

Road lighting and the role of central government

The history of road lighting is briefly traced. Central government did not play an active role until the Departmental Committee of 1935-37. Its influence on subsequent BSI Codes of Practice and its relevance to current international thinking are considered. The role of central government in finance, administration, design and practice is discussed. The paper deals with aspects such as international theory and practice and its relevance to Britain; road surface luminance, uniformity and glare restriction as related to cost; the effect of lighting on night accidents; a comparison of SOX and linear 1.p. sodium sources for motorways and trunk roads, along with the influence of central government on technical standards and hardware. Finally economic aspects are dealt with.