几种新型的星载多光谱和成像光谱仪

近几年出现了几种新型的星载多光谱和成像光谱仪,例如:Landsat-7卫星的有效载荷增强型主题测绘仪+（ETM+）;EOS AM-1卫星的有效载荷多角度成像光谱仪（MISR）和先进空间热发射和反射辐射计（ASTER）;特殊探测器紫外成像光谱仪（SSUSI）。文章从结构、性能参数等方面综述了这几种星载成像光谱仪。     

LANDSAT-7卫星的有效载荷ETM

LANDSAT-7卫星的主要有效载荷——改进型主题测绘仪(Enhanced Thematic Map-per Plus)ETM 是在landsat-4和Landsat-5卫星的主要有效载荷主题测绘仪(Thematic Map-per)的基础上改进的。ETM 相对TM的主要不同之处在于它增加了1个金色谱段和2个增益区域,增加了太阳定标器,并提高了红外谱段的分辨率,文章简要介绍ETM 的性能和主要组件。     

基于MNDWI水体指数的ASTER与ETM+影像交互比较研究

世纪之交以来相继发射的各种新型传感器给遥感领域带来了一个新的热门课题,即多种传感器影像之间的交互比较(Cross Comparison)。通过3对同日过空的ASTER与ETM+影像对,分别基于影像原始DN值、ICM模型反射率和IACM模型反射率数据来对这两种传感器影像的水体指数(MNDWI)进行综合对比,并提供了两种传感器MNDWI指数互为转换的关系方程。结果表明,ASTER与ETM+影像分别基于三类数据(DN、ICM、IACM)计算的MNDWI指数间,均存在很强的线性相关关系,决定系数都大于或接近0.9。精度验证表明,ASTER与ETM+影像MNDWI指数互为转换的关系方程具有很高的精度,其误差RMSE介于0.057～0.073之间;且以基于IACM模型反射率的结果最为稳定、精度最高。因此,推荐使用该模型数据来进行这两种传感器影像MNDWI指数的互为转换。     

Built-up land mapping capabilities of the ASTER and Landsat ETM+ sensors in coastal areas of southeastern China

Worldwide urbanization has accelerated expansion of urban built-up lands and resulted in substantial negative impacts on the global environments. Precisely measuring the urban sprawl is becoming an increasing need. Among the satellite-based earth observation systems, the Landsat and ASTER data are most suitable for mesoscale measurements of urban changes. Nevertheless, to date the difference in the capability of mapping built-up land between the two sensors is not clear. Therefore, this study compared the performances of the Landsat-7 ETM+ and ASTER sensors for built-up land mapping in the coastal areas of southeastern China. The comparison was implemented on three date-coincident image pairs and achieved by using three approaches, including per-band-based, index-based, and classification-based comparisons. The index used is the Index-based Built-up Index (IBI), while the classification algorithm employed is the Support Vector Machine (SVM). Results show that in the study areas, ETM+ and ASTER have an overall similar performance in built-up land mapping but also differ in several aspects. The IBI values determined from ASTER were consistently higher than from ETM+ by up to 45.54% according to percentage difference. The ASTER also estimates more built-up land area than ETM+ by 5.9–6.3% estimated with the IBI-based approach or 3.9–6.1% with the SVM classification. The differences in the spectral response functions and spatial resolution between relative spectral bands of the two sensors are attributed to these different performances.     

Recovering of the thermal band of Landsat 7 SLC-off ETM+ image using CBERS as auxiliary data

The failure of scan-line corrector (SLC-off) has resulted in the limited use of Landsat 7 ETM+ images. Considering its characteristics, many attempts have been conducted to recover the SLC-off ETM+ image. While much attention has been paid to recovering the optically multispectral bands, few researches have been done to reconstruct the thermal band. Main purposes of our study were to evaluate the possibility that using China Brazil Earth Resources Satellite (CBERS) as auxiliary data to recover the thermal band of SLC-off ETM+, and discuss the usage of the recovered one. The adaptive window linear histogram match (AWLHM) method was selected primarily, followed by the modified one. Results illustrated the feasibility of using the modified AWLHM method with the linear combination of CBERS-01 band3 and band4 to reconstruct the SLC-off thermal band. It encourages that further researches should be done to enable more scientific application of SLC-off ETM+, particularly its’ thermal band.