一种基于阴影像元的光学遥感大气校正方法

提出一种基于6S模型 阴影像元的大气校正方法,适用于有阴影像元存在的高空间分辨率光学遥感影像。该方法从阴影像元与非阴影像元的信号差异估算气溶胶光学厚度,与暗目标方法相比,此方法避免地表反射率的假定难题。以北京市密云县的IKONOS影像对方法进行验证。在气溶胶光学厚度的估算上,该方法的估算结果与MODIS气溶胶产品基本一致,而且其结果的稳定性明显好于暗目标法。在大气校正的结果方面,针对各类地物,比较大气校正前后的光谱与同类典型实测地物光谱,结果说明大气校正能够大大恢复各类地物光谱的典型特征,这将有利于地物的识别。最后通过比较大气校正前后的NDVI发现,大气校正能够明显增大高植被覆盖区与低植被覆盖区NDVI的差别,使植被信息更加突出。

A Method of Atmospheric Correction Based on Shadow-pixel for Optical Satellite Data

A new method of atmospheric correction for optical remote sensing imagery is presented.The method is applicable to optical remote sensing imagery with shadow pixels,such as high spatial resolution imagery.Aerosol Optical Thickness(AOT) is a very important parameter of atmospheric correction.The new method estimates aerosol optical thickness from the signal differences of shadow pixel and non-shadow pixel.IKONOS imagery of Miyun County,Beijing is used to validate the new method.The result of AOT estimation is basically the same as the MODIS AOT products,which proves the reliability of the new method to a certain extent.In addition,because the method avoids the surface reflectance assumption,it overcomes the uncertainty of the Dark Objective Method(DOS) and the stability of AOT estimation result has been greatly increased.Finally,the results of atmospheric correction and reflectance revival show that compared to apparent reflectance curve,atmospheric corrected reflectance curve is closer to measured typical objects reflectance curve.Besides,the difference of NDVI between high vegetation coverage and low vegetation coverage area after atmosphere correction is more obvious,so it can be said that atmosphere correction can make the vegetation information more prominent on the remote sensing imagery.