光学遥感对地成像过程中的邻近效应模拟分析

光学遥感的邻近效应可以看作大气点扩散函数(PSF)和地表辐射场的卷积,通过逆向蒙特卡罗法模拟大气PSF,利用辐射传输模型MODTRAN计算地表辐射场,获得遥感器入瞳处的辐亮度值.开展不同对比度目标背景物在典型条件下的邻近效应模拟与分析,结果显示:目标和背景的反射率分布对邻近效应影响很大,背景反射率越大,邻近效应占总辐射的比例越高;暗目标在亮背景下的邻近效应明显大于亮目标在暗背景下的邻近效应;固定成像高度和区域,空间分辨率越高,邻近效应越明显;地面气象视距对邻近效应的影响非常显著,气象视距增大,邻近效应减弱;太阳天顶角增大,邻近效应减弱.模拟结果为高分辨率光学遥感成像系统高精度建模和邻近效应校正算法研究提供了依据.

Simulation and analysis of the adjacency effect in earth-imaging process of the optical remote sensing

Adjacency effect of the optical remote sensing could be regarded as the convolution of the atmospheric point spread function(PSF) and the surface-leaving radiance. By simulating the atmospheric PSF with backward Monte Carlo method and calculating the surface-leaving radiance with MODTRAN model, the at-sensor radiance was obtained. The adjacency effects for different target and background under different propagation conditions were simulated and analyzed. The results show that target and background reflectivity affect adjacency effect significantly and the percentage of the radiance caused by the adjacency effect in the total radiance increases with the increase of the background reflectivity. Adjacency effect for dark target under bright background is more obvious than that for bright target under dark background. Given imaging height and area, the higher the imaging space resolution, the stronger the adjacency effect is. Effect of the surface meteorological range on adjacency effect is of high importance. The larger the surface meteorological range, the bigger the sun zenith angle, the weaker the adjacency effect is. These results could provide the basis for modeling the optical remote sensing imaging system with high precision and exploring the correction algorithm of the adjacency effect.