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随着定量遥感技术的发展,描述森林冠层二向反射分布函数(BRDF)的机理模型越来越多。该研究采用3种植被冠层BRDF模型——DART模型、4SCALE模型和MGEOSAIL模型,模拟了不同郁闭度样地在红光、近红外波段各个观测角度下的场景反射率,并比较分析了不同BRDF模型的适用性和局限性。结果表明:MGEOSAIL模型只适于模拟样地郁闭度较小、林木个体较大条件下的场景反射率,且热点效果不十分明显;DART模型和4SCALE模型适于任何郁闭度条件下的场景反射率的模拟,并且精度较高;4SCALE模型模拟的场景反射率介于DART模型模拟的1次散射与5次散射之间。这3种模型在模拟近红外波段的场景反射率时,均存在“碗边”效应。
With the development of quantitative remote sensing technology, there are more and more mechanistic models describing the canopy reflectance distribution function (BRDF) of the canopy. In this study, three kinds of vegetation canopy BRDF models - the DART model, the 4SCALE model and the MGEOSAIL model, were used to simulate the scene reflectivity in different canopy swaths under various observation angles in the red and near infrared bands. Applicability and Limitations of BRDF Model. The results show that the MGEOSAIL model is only suitable for simulating the scene canopy reflectance under larger conditions and the tree effect is not obvious, and the DART model and 4SCALE model are suitable for any scene with closed canopy density The reflectivity was simulated with high accuracy. The scene reflectivity simulated by 4SCALE model was between the first and the fifth scattering simulated by DART model. These three models have the “Bowl ” effect in simulating the scene reflectivity in the near infrared band.