地表的复杂性在可见光/近红外波段体现在由非均匀造成的交叉辐射影响和非朗伯双向反射特性两个方面,为此利用MODTRAN4和大气点扩散函数的解析近似分析了低空机载测量中影响交叉辐射的各种因素。结果显示,对于机载测量,大气交叉辐射影响随测量条件不同而改变,需要实时计算。为此,将改进的大气点扩散函数的解析近似算法结合MODTRAN4辐射传输模型,设计了校正大气交叉辐射影响的算法。对AMTIS图像的处理结果显示,该算法提高了地表反射比的计算精度。

The complexity of surface parameters can be characterized by cross radiance and BRDF in VIS/NIR band.In this paper,MODTRAN4 code and atmospheric point spread function were used for the simulation and analysis of the influences of a set of factors on cross radiance.The results show that the variance of cross radiance could be resulted from every factor,so it must be computed on the basis of measurement conditions.A new methodology is developed to eliminate cross radiance from total radiance based on modification of analytical solution of PSF and combination of it with radiation transfer code of MODTRAN.The applications to AMTIS image show a good precision.