一种测量天空亮度的新方法

A NEW WAY TO MEASURE SKY-LIGHT LUMINANCE DISTRIBUTION

本文介绍了一种测量天空亮度分布的新方法。这种方法利用视场角为180°的鱼眼镜头照相机和计算机数字图像处理系统,实现了天空亮度分布的瞬时测取和胶片密度的高效率处理。文中论述了胶片灰度与天空亮度的标定转换实验方法。引用了误差理论中的数据处理方法确定出二者间的函数关系。通过对昆明和重庆地区晴和阴天空下大量实测结果的误差处论和分析,得到了其相关系数和标准偏差的频数分布图,由此证明了这种方法的可靠性。

This paper introduces a new way to measure sky-light luminance distribution, the method employs a camera with a 180° fieldof-view fisheye lens and a computer digital image processing system, which ensure a short time measurement of sky-light luminance distribution and an efficient processing on the density of the film. It discusses the laboratory definite converting between the grey level on the film and sky-light luminance. With the data processing method in error theory, it finds out the functional reation between the two. Through the pro cessing and analysis of measurements of clear and overcast sky taken in Kunming and Chongqing. The coefficient of correlation and the computational value and frequency distribution diagram of standard error of estimation are obtained. Hence the reliability of such measurement is proved.