基于图像亮度的实际天空类型识别

Real Sky Type Identification Based on Image Intensity

天空亮度分布是建筑采光设计及节能分析的重要技术依据。国际照明委员会(CIE)给出了天空亮度的计算方法。这一方法首先要确定实际天空类型,而确定天空类型需要采用全数字亮度计,或者通过计算天空指数值的方法。本文提出一种应用手机摄像头拍摄天空图像,利用亮度方程和散射函数计算天空亮度值,应用最小方差准则,确定基于CIE一般天空标准的实际天空类型,为进一步天空亮度计算提供数据支持。

Sky intensity distribution is an important technical basis in architectural lighting design and energyefficient analysis. A computational method is provided by the International Commission on Illumination（ CIE）. In this method,the real sky type must be identified firstly,which is accomplished by all digital luminance meter,or through calculating the sky index. In this paper,the method of image measurement using the mobile phone camera is introduced,and the sky intensity is obtained by using intensity formula and scaled luminance ratio function,which is optimized by the sense of linear minimum variance. The real sky type is recognized based on the CIE Standard General Sky. This paper provides data support for further calculation of sky intensity.