基于全视野数字图像的能见度估算方法  

A Visibility Estimation Method Based on Digital Total-sky Images

作　　者：陆天舒[1] 杨俊[1] 邓敏 杜传耀 Lu Tianshu;Yang Jun;Deng Min;Du Chuanyao(Laboratory of Lightning Physics and Protection Engineering/State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences,Beijing100081;Conghua Meteorological Bureau of Guangdong,Guangzhou501900;Beijing Municipal Meteorological Observation Center,Beijing100176)

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室/雷电物理和防护工程实验室,北京100081 [2]广东省广州市从化区气象局,广州501900 [3]北京市气象探测中心,北京100176

出　　处：《应用气象学报》2018年第6期701-709,共9页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(41675030);国家重大科学仪器设备开发专项(2012YQ11020504);中国气象科学研究院基本科研业务费项目(2015Y010).

摘　　要：基于全视野数字图像的能见度估算方法是将全视野图像大气透射率与大气能见度通过曲线拟合方法建立联系,得到估算模型进行能见度估算。首先通过历史全视野图像和对应时刻的大气能见度建立样本数据集,再利用暗原色先验理论获取全视野图像大气透射率,通过多项式拟合方法建立离散样本数据集中大气透射率与对应时刻大气能见度的关系,即全视野图像能见度估算模型,最终将所需估算时刻的数字图像输入估算模型进行能见度估算,得到大气能见度数值。结果表明:建立的基于全视野数字图像能见度估算模型在环境光照均匀时大气能见度估算值与能见度实测值有较好的一致性,可作为前向散射仪的补充观测方法,弥补其采样存在的局限性。The proposed visibility estimation method is a curve fitting algorithm,which establishes a relation between the image's atmospheric transmittance and atmospheric visibility.Firstly,the total-sky image is captured by the digital total-sky image visibility experimental platform.The core unit of this platform is a digital camera equipped with a fisheye lens,and the camera is placed vertically towards the sky.The platform can collect a total-sky image at specified time interval,and then the original image is transferred to a computer for image processing.In particular,the total-sky image needs to be converted into a panoramic image using an image calibration algorithm,and the panoramic image contains most of the near-surface image information.Next,the panoramic image is used to compute the visibility.Some visibility-related image features are extracted from the panoramic image firstly.The image's atmospheric transmittance can be calculated using dark channel prior theory.The relationship between the atmospheric transmittance and atmospheric visibility can be estabIished by curve fitting method,and the initial visibility estimate model based on total-sky images is achieved.The model can be improved by combining a number of field experiments.Finally,the retrieved visibility is calculated by importing the real-time total-sky image into the model. Results show that the basic trend of visibility data from total-sky visibility estimation model is consistent with that of the forward scattering visibility meter through the comparative test and calculating correlation coefficients.The trend is most noticeable in low or medium visibility.However,as the visibility increases,the consistency decreases because of more fluctuation.As the forward scattering visibility meter used to establish the model whose measuring range is from0to35km,estimate model results are generally less than the measurement of forward scattering visibility meter especially when the visibility is high.In general,the basic trend of visibility data of total-sk

关 键 词：全视野图像 暗原色先验 数字图像处理 能见度 

分 类 号：P412.17[天文地球—大气科学及气象学]