嫦娥一号干涉成像光谱(IIM)数据再处理研究
Study on Reprocessing of Chang'E-1 Interference Imaging Spectrometer (IIM) Data
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摘要: 嫦娥一号卫星搭载的干涉成像光谱仪(Interference Imaging Spectrometer, IIM)用于获得月表元素的含量. IIM光谱左右色调不均一, 影响元素制图精度, 因此有必要对其进行平场校正, 消除探测器各像元的光谱响应不一致对图像产生的影响. 在嫦娥一号卫星在轨运行1 yr期间(2007年10月至2008年10月), 干涉成像光谱仪共获得576轨数据, 之前已有学者进行过平场校正, 但是校正结果不能适用于月表所有地区. 结合了2008年11月和12月获得的130轨数据, 采用基于光谱特征的反射率归一化方法, 通过选取大量太阳矢量与卫星轨道面夹角beta对称的轨道中的均一平坦、无曝光过度地区的光谱数据, 对其平均求得平均行, 利用平均行求得校正因子实现平场校正. 对比校正前后光谱图像和反射率曲线, 月球不同地形的色调不均一现象和条纹均得到有效的消除, 这将有利于后续元素的反演和实际应用.Abstract: The Interference Imaging Spectrometer (IIM) onboard the Chang'E-1 satellite was used to retrieve the content of elements of the moon. The hue of IIM spectral images is inhomogeneous from left to right, which affects the retrieval of elements. Therefore, flat-field correction is necessary to eliminate the effects of the inhomogeneous spectral response of each pixel of the detector on the image. The IIM obtained a total of 576 orbits data during the one-year operation of the Chang'E-1 satellite (October 2007 to October 2008). Scholars have done flat-field correction before, but the correction results could not be applied to all regions of the moon. This paper combines the 130 orbits data obtained in November and December 2008, and proposes the reflectance normalization method based on spectral features. By selecting a large number of homogeneous, flat, and non-overexposed spectral data in beta-angle symmetrical orbits, the average row is obtained by averaging the selected data, and using the correction factors which are obtained by the average row to finish flat-field correction. Comparing the spectral images and reflectance curves before and after the correction, the inhomogeneity of hue and streaks in different terrains of the moon are effectively eliminated, which will be beneficial to the subsequent elemental retrieval and practical application.