云辐射图像的分析处理

【作者】 付娴娴；

【导师】 吴健；

【作者基本信息】 电子科技大学 ， 光学， 2007， 硕士

【摘要】 本文主要以云为研究对象，首先从理论上研究块状云的辐射特性，并得到一些结论；其次将实验与图像处理相结合，找到一套处理云图像的方法，为以后利用实际获取的天空图像研究云的辐射亮度特性作准备。主要研究成果如下：(1)根据块状云的特点，利用Monte-Carlo法和δ-Eddington近似的方法求解了块状云的三维辐射传输方程。利用Monte-Carlo法得到了太阳辐射通过立方体云块后，立方体云块各侧面的向上和向下的辐射情况；利用δ-Eddington的方法，得到了太阳辐射通过孤立云块后，孤立云块的反射率随云的厚度、水平尺寸及太阳天顶角取不同值时块状云顶面平均反射率的变化情况。(2)建立了一套专门获取天空图像的实验系统，利用相机(宾得IstDL型号)和长焦镜头(三星55mm～200mm)每天同样的时间、同样的地点、同样的方位对天空拍摄照片。(3)得到一套处理天空图像(云图像)的方法，对实验获得的天空图像进行数字图像处理，包括变为灰度图、图像压缩、画出图像的灰度直方图、双图灰度比较、求图像相关长度、画出图像的灰度三维图等，利用这些方法，提取图像中的有用信息，为以后研究云的辐射亮度分布规律做准备。(4)利用图像处理结果，提出三种模拟云的方案，分别是相关长度法、灰度叠加法和分形几何法，并根据模拟云过程中所遇到的问题，指出各种方法的优缺点和可行性。(5)在云的相对辐射亮度的基础上，采用分形几何的方法模拟云，并利用分形插值的方法模拟了有云的天空场景。更多还原

【Abstract】 Clouds were mainly described in this thesis. Firstly radiation characteristic of the blocky clouds were theoretically talked about, and some conclusions were got. Secondly in order to prepare for researching clouds’ radiation luminance characteristic with real sky pictures, experiments were combined with image processing, and a suit of method was got to deal with clouds pictures.The main research results were as follow:(1) Accorded to the blocky clouds’ characteristic, Monte-Carlo and d-Eddington approximate methods were used to solve the three-dimensional radiation transfers equation of the blocky cloud. When using Monte-Carlo method, every side of cubic clouds’ downward and upward radiation characteristic was got. When using d-Eddington method, isolate clouds’ reflectivity changed with thickness, horizontal size and the sun day vertex angle were got.(2) A suit of experimental facilities was set up to get sky images. The camera (IstDL type) and the lens (55mm-200mm) were used to get sky image at the same time, same place and same position every day.(3) A suit of method was set up to deal with sky images (cloud images), including turning into grey image, image compression, drawing image grey histogram, comparing with two images’ grey value, getting image relevant length, drawing image’s three-dimension of grey level etc. In these methods, useful information was got for researching cloud radiation luminance.(4) Image process’s results were used, and three schemes were put forward to simulate cloud, including relevant length method, grey superpose method and fractal method. Accorded to the questions that we met in simulating clouds, every method’s advantage, disadvantage and every method’s feasibility were pointed out.(5) On the basis of clouds radiation luminance, fractal method was used to simulate clouds. And fractal interpolation method was used to simulate sky scene with clouds.更多还原