基于图像融合的反照率产品降尺度方法研究

提出了一种基于物理意义图像融合的反照率降尺度算法,用以增强现有全球陆表特征参量(GLASS)反照率产品的空间分辨率,快速生成高分辨率反照率。首先对GLASS反照率产品和HJ反射率数据进行预处理,包括图像重投影、图像裁剪、雪像元和无效值像元掩膜;然后基于朗伯假设,将HJ反射率数据通过窄波段到宽波段的转换得到初级的高分辨率反照率;在此基础上将低分辨率的GLASS反照率产品与高分辨率的HJ数据进行融合得到高分辨率的反照率产品,其中考虑了GLASS产品的空间响应;最后分析了融合得到的高分辨率反照率影像,并使用黑河中游地面实测数据对融合结果进行了验证。结果显示:利用基于物理意义图像融合的反照率降尺度算法得到的高分辨率反照率产品精度较高(RMSE为0.02左右),并且该方法快速高效,具有推广和发展成为业务化算法的潜力。

A Study of Albedo Product Downscaling Method based on Image Fusion

An albedo downscaling algorithm based on image fusion with consideration of physical meaning was proposed to enhance the spatial resolution of the Global LAnd Surface Satellite (GLASS) albedo product and produce high\|resolution albedo rapidly.Firstly,data processings including image reprojection,image cropping,snow pixels masking were conducted for 1km GLASS albedo and 30m multiband reflectance acquired by the CCD sensor onboard the Chinese satellites HJ1A/1B (short for HJ/CCD).Secondly,the preliminary high\|resolution albedo was estimated by HJ/CCD reflectance through the method of narrowband to broadband conversion.Thirdly,considering the spatial response of GLASS albedo,the coarse\|resolution GLASS albedo and the preliminary high\|resolution albedo were fused to yield the final high\|resolution albedo.In the end,the fusion albedo with high spatial resolution was shown,analyzed and validated with In Situ data of middle Heihe River Basin.The results show that the high\|resolution albedo obtained by downscaling algorithm based on image fusion of physical meaning is with high precision (RMSE was 0.02 or so),and the algorithm is fast and efficient,indicating its potential to become an operational algorithm for high\|resolution albedo product.