利用MODIS数据和查找表的城区TM影像大气校正

影像大气校正精度的关键参数为气溶胶光学厚度,而城区大气条件复杂,对城区TM影像采用统一的大气参数进行大气校正,势必难以获得令人满意的校正精度。因此,本文提出了一种基于MODIS数据和查找表的大气校正算法,首先应用6S模型离线计算建立不同气溶胶光学厚度的大气校正系数查找表,然后基于MODIS数据反演气溶胶光学厚度,最后基于查找表和气溶胶光学厚度数据对长沙城区TM影像进行了逐像元大气校正。结果表明:基于查找表的校正算法与6S模型在线计算算法的校正精度接近,能够较好地进行大气校正;在水体区校正精度最高,而在城区校正精度相对较低。

An atmospheric correction algorithm for urban area TM data based on MODIS data and look-up table

Aerosol optical depth is the key parameter that influences the result of atmospheric correction.Traditional methods presume that the atmospheric condition is homogeneous,but it is not true for the urban area,therefore,traditional methods can not get accurate result of atmospheric correction.To resolve this problem,an atmosphere correction algorithm based on look-up table and MODIS data was proposed in the paper.First,the look-up tables of correction parameters for different aerosol optical depth values were established by the 6S model offline computation,then,aerosol optical depth was retrieved from MODIS data,finally,the TM data Changsha city was corrected making use of the look-up table and aerosol optical depth derived from MODIS data.Comparing the result of look-up table algorithm and 6S online algorithm,it was found that: the difference of the results from two algorithms is small,and the look-up algorithm could get accurate atmospheric correction result;the precision on water area was best,and that of urban area was worse comparing with the water area and vegetation area.