基于偏振原理的水面反射光的剥离
Correction of skyglint above water surface based on polarized principle
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摘要: 水面的镜面反射是影响水环境遥感的关键因素之一。通过分析气-水界面反射光的偏振特性,从多角度偏振遥感的角度,提出一种剥离水面反射光的方法,并通过室内实验进行了验证。将ASD光谱仪与线偏振片结合扩展成高光谱偏振传感器,获取不同观测天顶角时水面反射光的偏振光谱。结果表明,当探测角不满足布儒斯特角时,在偏振片的主消光方向能剥离绝大部分的水面反射光;当入射角越接近布儒斯特角,其剥离效果越佳;以布儒斯特角观测时,可以达到完全剥离的效果。即该方法能显著削弱、甚至完全剥离水面的反射光,直接获取离水辐亮度,对于提高水色遥感的精度有着重要的应用价值。Abstract: The specular reflected light above water surface,including sun-glint and skyglint,is one of the key factors that affect remote sensing of water color.This paper aims to correct the sun-glint and sky-glint effects in measurements of upward radunce from water surface based on the polarized principle and the multi-angle polarized remote sensing.A polarization filter was placed in front of the sensor of ASD field spectrometer to obtain the polarized characteristics of water surface spectrum in various conditions.By contrast with the spectral obtained under different incident geometry and polarized conditions,the experimental results show that the reflected light can be corrected completely with an incident zenith angle of 53 degree (Brewster's angle) and zero polarized angle.And most of the reflected light can be corrected with a random incident angle and zero polarized angle.In conclusion,the reflected light can be reduced obviously or even removed completely based on the polarized principle,which provide important value to improve the accuracy of water color remote sensing.