摘要
清洁水体光谱在可见光和近红外波段的反射率比较低,其光谱特征不明显,在光学遥感图像上水体一般都表现为暗色调,造成了利用光谱学手段进行水体遥感识别和水质参数反演的困难。在研究水体的偏振波谱时作者发现,在对水体进行多角度观测时,水体在可见光与近红外波段的偏振度波谱值要远大于其无偏的反射率,表现在图像上即水体的偏振度图像的亮度要远大于其强度图像的亮度,文章对这种现象和规律进行了物理学解释,并利用法国PARASOL多角度偏振卫星遥感图像数据对这个规律进行了验证。该文首次揭示了利用多角度偏振遥感进行水体探测的优势,该方法有效解决了在利用光学遥感进行水体探测时反射率低的难题,大大提高水体的遥感识别能力和水质参数反演精度。
The reflectance of pure water is very low at visible and near infrared bands. Its spectral characteristics are not obvi ous. Water always shows dark hue in optical remote sensing images. This dark hue causes the difficulties in water remote sens ing identification. There is an interesting phenomenon when the authors research the water polarization spectroscopy. The au thors measured water＇s polarization spectra and reflectance spectra at different view zenith angles using the ASD spectrometer,When the view zenith angle was zero （measured vertically）, as the spectrum people commonly measure, there was no polariza- tion phenomenon at the water surface, and the reflectance was low at each band. Along with the increase in view zenith angle, the DOP spectra curves increased evidently, while the reflectance curves only changed a little. When the view zenith angle was o- ver 30 degree, the values of DOP spectrum were much larger than the reflectance spectrum values at the entire visible and near infrared bands. At some bands, the DOP value was several dozen times than its reflectance value. This phenomenon shows that the water＇s brightness in DOP image is much higher than its brightness in intensity image under the same condition. This rule was verified by the PARASOL multiangle polarization satellite data. Comparing the average brightness of DOP images with the average brightness of intensity images at 490, 670 and 865 nm band, the former is higher than the latter apparently. The brigh- ter DOP images are better for water remote sensing identification. It is the first time that the authors found this special multian- gle polarization spectral character of water. It revealed the advantage of water detection using the multiangle polarization remote sensing data. This method solved the low reflectivity problem of water color remote sensing. It will greatly improve the capability of water remote sensing identification and the retrieval accuracy of water quality parameters.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2010年第2期448-452,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(40771153
60808035)
北京市自然科学基金项目(1093016)资助
关键词
光谱
偏振
多角度
遥感
水色
Spectrum
Polarization
Multi-angle
Remote sensing
Water color
