| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for evaluating all-sky photoenvironment capable of carrying out accurate analysis/evaluation by using a small-sized simple apparatus. SOLUTION: Hemispherical photographs are taken by using a digital camera 12 and a frequency distribution curve of pixel values in which pixel values which are quantities of light every pixel of the photographed images are taken along an abscissa and frequency of appearance every pixel value of the photographed images is exhibited along an ordinate is obtained and a pixel value in which curvature of the frequency distribution curve becomes maximum, based on the resultant frequency distribution curve, is defined as a threshold value for separating a light-shielding article from the sky which becomes a light source. The number of pixels having a pixel value larger than the threshold value is obtained and a pixel value larger than the threshold value is sampled. Values obtained by multiplying a cosine value of angle of each sample to an axis turning toward zenith are accumulated to provide a whole sky photoenvironment value and a value obtained by dividing the photoenvironment value under each photoenvironment with the photoenvironment value kept in a state free from a shielding article in whole the sky is evaluated as a relative quantity of light at the place. COPYRIGHT: (C)2005,JPO&NCIPI |
