光学卫星成像主要是通过传感器接收地表对太阳入射光线的反射、地表辐射和大气散射等能量,形成影像数据。卫星侧视成像时,太阳与卫星之间的位置关系随日期、地理位置和地方时变化,当条件适当时,两者处于对称关系,从地面上看类似镜面反射状态。此时,由于地表的非朗伯性,就使卫星接收的反射能量偏高,造成接收得到的图像亮度高于正常水平,甚至过饱和而不可用。本文以SPOT卫星为例,从卫星的观测方位和太阳的照射方位入手,讨论卫星观测方位对遥感成像质量的影响。经分析,每年5—9月期间,在北纬32°—45°地区,当SPOT卫星以较大的侧视角向左侧成像时,卫星观测方向和太阳入射方向在成像区投影共线并且太阳的高度角与卫星的高度角近似相等的可能性很大,从而影响卫星成像的质量。

Optical satellite remote sensing mi agery is acquired by receiving the reflection of the sun incidence rays, the earth surface radiation and atmospheric dispersion by sensor. If the satellite’s observation from sideviewing, the relative position between sun and the satellite changes with date, geography position and local tmie, however, if all the conditions are proper, the sun and the satellite could be symmetricalwhich is smi ilar to the specular reflection observed on the ground. In this case, the brightness ofacquired mi age ismuch higher than normal situation, and the reflection energy acquired by the satellite is too high because of the non-uniform reflection ofearth’s surface. Sometmi es the mi age is too supersaturated to use. Thispaper studies the influence on the quality of remote sensing mi age, which is caused by the satellite observation direction and sun illumination direction. After analyzing the influencewith SPOT mi agery data, it is found that the satellite and sun are probably in the specular reflection position, when satellite observes the area between north latitude 32° and 45°with large inclination angle to left side off the track during the date from May to September. This situationwillhave negative influence on satellite remote sensing mi agery.