Topographic Correction of the SELENE MI Images with the LOLA DEM around Shackleton Crater
Topographic Correction of the SELENE MI Images with the LOLA DEM around Shackleton Crater
复制标题
使用沙克尔顿陨石坑周围的 LOLA DEM 对 SELENE MI 图像进行地形校正
DOI：
10.3390/rs14194739
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发表时间：
2022
期刊：
影响因子：
5
通讯作者：
X. Tong
中科院分区：
文献类型：
--
作者：
Xiaoxue Ke;Chao Wang;Jinhuan Du;Yuting Yuan;Xiong Xu;Yongjiu Feng;Huan Xie;Shijie Liu;X. Tong
由于月球南极地区地形复杂，光照条件极端，地形对该地区的反射率有一定的影响。这可能导致对月球表面性质的误解。因此，利用日本第一颗月球轨道飞行器SELENE（SELenological and ENglomerate Explorer）上搭载的多波段成像仪（MI）获得的沙克尔顿陨石坑的图像来评估地形对极地反射率的影响。三种方法，即，B校正、C校正和Minnaert校正应用于MI图像以减少地形影响。结果表明，C校正的反射率结果存在过校正现象。在用Minnaert校正导出的反射率中，地形效应被放大，而不是被抑制。相比之下，B校正是更合适的方法，在整个研究区域的MI图像的地形校正。在研究区域，火山口壁的阳光照射斜面的反射率下降了约60%。陨石坑外的反射率比陨石坑壁的反射率下降了约20%。同时，根据局部太阳入射角的余弦与校正后的反射率的相关性，MI图像中的地形效应似乎没有完全消除。然而，通过分析1250 nm波段的光谱吸收特征，我们可以将这种“残留”效应归因于沙克尔顿陨石坑内外的不同成分，很可能是由高浓度的斜长石造成的。还对美国航天局候选着陆区的MI图像进行了地形校正。结果表明，地形效应对日照坡面的反射率有显著的影响，在分析反射率图像时不应忽略。这项研究强调了地形对月球南极表面反射率的影响。此外，我们的研究结果还表明，在评估特定区域的地形校正时，应考虑各种地形下的成分差异，如沙克尔顿陨石坑的内壁。
Due to the complicated terrain and extreme illumination condition in the lunar south polar region, topography has an impact on the reflectance of the area. This may result in the misinterpretation of the properties of the lunar surface. Therefore, an image obtained across Shackleton Crater by the Multi-band Imager (MI) onboard the first Japanese lunar orbiter SELENE (SELenological and ENgineering Explorer) was utilized to evaluate the topographic effect on the reflectance of the polar region. Three methods—i.e., b correction, C correction, and Minnaert correction—were applied to the MI image to reduce the topographic effect. It was found that the reflectance result of C correction suffers from overcorrection. The topographic effect is enlarged, rather than suppressed, in the reflectance derived with Minnaert correction. Comparatively, b correction is the more appropriate method for the topographic correction of the MI image across the study area. The reflectance of the sunlit slope of the crater wall in the study area decreased by ~60%. The reflectance of the area outside of the crater, with a gentler slope compared to the crater wall, decreased by ~20%. Meanwhile, according to the correlation of the cosine of the local solar incidence angle and the corrected reflectance, the topographic effect was seemingly not completely eliminated in the MI image. However, by analyzing the spectral absorption features of the 1250 nm band, we can attribute this “residual” effect to the different compositions inside and outside of Shackleton Crater, most likely caused by a high concentration of plagioclase. Topographic correction of the MI images over NASA candidate landing regions was also conducted. The results suggest that the topographic effect can contribute significantly to the reflectance of the sunlit slopes, and should not be neglected in the analysis of the reflectance images. This study highlights the topographic impact on the reflectance of the lunar south pole’s surface. In addition, our results also suggest that the compositional differences under various terrains should be considered in the evaluation of the topographic correction of specific regions, such as Shackleton Crater’s inner walls.