What kind of illuminance do we need for sports lighting. Sports shomei no sekkei, suiheimen shodo wa banno ka

Problems in the application of horizontal illuminance, which is defined by JIS's illuminance standard, lighting for outdoor sports facilities, and lighting for indoor gymnasiums, to designing of sports lighting were described. Significance in the novel introduction of concept of spatial illuminance, such as semi-cylindrical illuminance, in addition to conventional concept of horizontal and vertical illuminances was also discussed. From the relation between brightness and illuminance, it was made clear that a method for expressing the illuminance of three-dimensional objects was necessary. A concept of spatial illuminance, such as spherical, hemispherical, cylindrical, and semi-cylindrical illuminances was generally remarked on the basis of a theory of light field.'' A definition of a ratio of cylindrical illuminance to horizontal illuminance was proposed as a defining method of required level of brightness. Based on the concept of hexahedral illuminance given by the Commettee of Illuminating Engineering (CIE), it was estimated that sufficient brightness can be obtained in the case the value of bcylindrical illuminancec/bhorizontal illuminancec was in the range between 0.5 and 2.0. 9 refs., 4 figs.