月球是人类深空探测的前哨站。 月球卫星光谱测量是月表岩矿成分分析的主要技术方法。 鉴于月表比地球地形起伏还要显著, 有必要开展月球卫星高光谱数据的地形校正。 通过顾及宏观地形起伏和周围地形反射辐射的影响, 建立适合月表的Sandmeier辐照度模型, 并由此推到了月表反射率地形校正模型。 以月球虹湾地区KAGUYA卫星Spectral Profiler(SP)高光谱数据为例, 借助美国Lunar Orbiter Laser Altimeter(LOLA)高程数据, 计算了试验区坡度、 坡向, 以及入射角、 反射角、 地形可见因子等地形校正参数, 结合平坦月表接收的太阳直接辐照度, 实现了月球虹湾地区经向SP数据的反射率校正。 通过比较发现, 校正后反射率像元数量统计直方图近似高斯分布, 而且光照区的月表反射率得到了抑制,阴影区的月表反射率有所增强, 有效地消除了月表起伏地形的影响。

The Moon may be considered as the frontier base for the deep space exploration. The spectral analysis is one of the key techniques to determine the lunar surface rock and mineral compositions. But the lunar topographic relief is more remarkable than that of the Earth. It is necessary to conduct the topographic correction for lunar spectral data before they are used to retrieve the compositions. In the present paper, a lunar Sandmeier model was proposed by considering the radiance effect from the macro and ambient topographic relief. And the reflectance correction model was also reduced based on the Sandmeier model. The Spectral Profile (SP) data from KAGUYA satellite in the Sinus Iridum quadrangle was taken as an example. And the digital elevation data from Lunar Orbiter Laser Altimeter are used to calculate the slope, aspect, incidence and emergence angles, and terrain-viewing factor for the topographic correction. Thus, the lunar surface reflectance from the SP data was corrected by the proposed model after the direct component of irradiance on a horizontal surface was derived. As a result, the high spectral reflectance facing the sun is decreased and low spectral reflectance back to the sun is compensated. The statistical histogram of reflectance-corrected pixel numbers presents Gaussian distribution. Therefore, the model is robust to correct lunar topographic effect and estimate lunar surface reflectance.