表面粗糙度对黑云斜长片麻岩不同探测角偏振度波谱影响研究

Influence of Surface Roughness on Degree of Polarization of Biotite Plagioclase Gneiss Varying with Viewing Angle

以黑云斜长片麻岩为例,探讨了表面粗糙度因子在350～2 500nm波段对岩石不同天顶角及方位角偏振度探测的影响,并在特征波段进行了定量分析。表明不同粗糙度的岩石表面,入射天顶角一定时,在镜面反射方位,偏振度随探测天顶角先是上升,到达最高值后又开始下降。(520±10)nm波段的偏振度在探测天顶角方向达到的最大峰值与表面粗糙度进行相关分析,发现他们呈幂函数关系。回归方程为:y=0.604x-0.297,可决系数R2为0.985 4。峰值所在天顶角度与表面粗糙度相关模型为,y=3.419 4x+51.584,y<90°,模型可决系数R2为0.817 7。偏振度随探测方位角变化的规律为以180°方位时偏振度最大,向两侧随探测方位离180°越远逐渐越低,并趋于0。(520±10)nm波段的偏振度在探测方位角180°方向达到的最大峰值与表面粗糙度进行相关分析,发现他们呈幂函数关系。回归方程为:y=0.582 2x-0.333,可决系数R2为0.984 3。对以上回归模型进行F检验,发现偏振度峰值及所对应角度与粗糙度之间存在显著的相关关系。

Polarized reflectance is influenced by such factors as its physical and chemical properties,the viewing geometry com-posed of light incident zenith,viewing zenith and viewing azimuth relative to light incidence,surface roughness and texture,sur-face density,detection wavelengths,polarization phase angle and so on.In the present paper,the influence of surface roughnesson the degree of polarization（DOP）of biotite plagioclase gneiss varying with viewing angle was inquired and analyzed quantita-tively.The polarized spectra were measured by ASD FS3spectrometer on the goniometer located in Northeast Normal Universi-ty.When the incident zenith angle was fixed at 50°,it was showed that on the rock surfaces with different roughness,in thespecular reflection direction,the DOP spectrum within 350～2 500nm increased to the highest value first,and then began to de-cline varying with viewing zenith angle from 0°to 80°.The characterized band（520±10）nm was picked out for further analysis.The correlation analysis between the peak DOP value of zenith and surface roughness showed that they are in a power functionrelationship,with the regression equation：y=0.604x-0.297,R2=0.985 4.The correlation model of the angle where the peak isin and the surface roughness is y=3.419 4x＋51.584,y90°,R2=0.817 7.With the detecting azimuth farther away from180°azimuth where the maximum DOP exists,the DOP lowers gradually and tends to 0.In the detection azimuth 180°,the cor-relation analysis between the peak values of DOP on the（520±10）nm band for five rocks and their surface roughness indicatesapower function,with the regression equation being y=0.582 2x-0.333,R2=0.984 3.Ftests of the above regression models in-dicate that the peak value and its corresponding viewing angle correlate much with surface roughness.The study provides a theo-retical base for polarization remote sensing,and impels the rock and city architecture discrimination and minerals mapping.