邻坡反射辐射对地物反射率计算的影响评估

Impact Evaluation of Neglecting Radiance Reflected from Neighboring Slopes on Calculating Target Reflectance

采用朗伯体经验模型计算邻坡反射辐射,并建立其对目标像元反射率计算影响的评估模型。研究表明,忽略邻坡反射辐射将造成目标像元反射率的计算值偏高,尤其在低照度区域易导致光学遥感影像地形辐射校正出现过饱和现象。研究证实,雪的可见光近红外波段的邻坡反射辐射、植被的近红外波段的邻坡反射辐射对目标像元反射率计算的影响显著,对地形遮蔽度大的目标像元可产生10%以上的反射率相对误差。

The radiance reflected from neighboring slopes is calculated with an empirical Lam- bertian model. An assessment model is developed to analyze relative error of target reflec- tance when neglecting incoming irradiance is neglected from surrounding terrain which will cause the reflectance of target pixel to be overestimated. The overestimation of reflectance will be stronger in shaded areas, which could bring more saturation value in topographically corrected image. The results show that radiance reflected from neighboring vegetation in near-infrared spectrum and neighboring snow in the visible and near-infrared spectrum should be accounted when we compute the reflectance of targets. Especially in the case of deep val- leys, the overestimation of target reflectance could be more than 10~/00 when the radiance is neglected.