大气对垂直遥感和大倾角遥感影响的主要差别之一体现于邻近象元的影响，对于垂直遥感，点扩散函数是各向同性的，即邻近象元对于目标象元的影响只与它们之间的距离有关，和它们之间的相对方位无关，但是对于大倾角遥感，点扩散函数不仅依赖于邻近象元和目标象元之间的距离，而且还依赖于它们之间的相对方位，在距离相同时，在观测方位上的邻近象元对目标象元的影响最大。本文用传感器，目标象元和邻近元构成的几何关系描述来自邻近象元的漫反射再经大气的一次散射而达到传感器的辐射通量，从而得到大气的点扩散函数的近似解析解，这种解析近似同蒙托卡洛的模拟结果有很好的一致，我们用这种方法得到了ASAS（Advanced Solid-state Array Spectroradiameter)大倾角观测时的大气的点扩散函数，并设计了一个Wiener滤波器去除邻近象元的影响，视觉效果评价和空间相关性分析的结果表明了这种方法的有效性和可行性。

One of the main difference between atmospheric effect on nadir and off-nadir observations is the adjacency effect. For nadir remote sensing,the adjacency effect is azimuthally isotropic, but in off-nadir remote sensing,the effect is azimuthally dependent and the contribution of the background in the direction of the observer is greater than others. In this paper,we consider the space composed by the sensor,the target pixel, and environmental pixel and use geometric relations to describe the single scattering of diffuse reflection from the environmental one toward the sensor,in order to get a first-order aproximation of the atmospheric PSF for off-nadir observation. Our approximation is compared with Monte Carlo simulation results. Then we design a Wiener filter to remove the adjacency effect on ASAS images. The correction results are evaluated by visual evaluation of image quality and the analysis of spatial correlation between pixels in the original,corrected offnadir and nadir images.