论文标题
从冠层反射率中提高方向区域散射因子（DASF）的估计：理论基础和验证
Improving the estimation of directional area scattering factor (DASF) from canopy reflectance: theoretical basis and validation
论文作者
论文摘要
方向区域散射因子（DASF）是用于植被监测的关键冠层结构参数。它提供了一种有效的工具，可将冠层结构和叶片光学材料从冠层反射率中解耦。当前从树冠双向反射率因子（BRF）估算DASF的标准方法基于以下假设：在弱吸收的710至790 nm光谱间隔中，随着干物的浓度，叶片散射不会太大变化，因此可以忽略其变异。这导致了DASF的偏见估计，因此导致与DASF相关应用的不确定性。这项研究提出了一种新的方法来说明这种生化成分浓度的变化，该方法还使用了2260 nm的冠层BRF。在对拟议方法的计算机分析中，一单位和三维场景的相对均方根误差（RRMSE）分别分别通过相对均方根误差（RRMSE）为49％和34％的标准技术的准确性显着提高。与文献中报道的室内多角质高光谱测量值相比，针叶的平均绝对误差降低了68％，阔叶檐棚的平均误差降低了20％。因此，提出的DASF估计方法的表现优于当前的估计方法，并且可以在与DASF相关的应用中更可靠地使用，例如功能性状，动力学和辐射预算的植被监测。
Directional area scattering factor (DASF) is a critical canopy structural parameter for vegetation monitoring. It provides an efficient tool for decoupling of canopy structure and leaf optics from canopy reflectance. Current standard approach to estimate DASF from canopy bidirectional reflectance factor (BRF) is based on the assumption that in the weakly absorbing 710 to 790 nm spectral interval, leaf scattering does not change much with the concentration of dry matter and thus its variation can be neglected. This results in biased estimates of DASF and consequently leads to uncertainty in DASF-related applications. This study proposes a new approach to account for variations in concentrations of this biochemical constituent, which additionally uses the canopy BRF at 2260 nm. In silico analysis of the proposed approach suggests significant increase in accuracy over the standard technique by a relative root mean square error (rRMSE) of 49% and 34% for one- and three dimensional scenes, respectively. When compared with indoor multi-angular hyperspectral measurements reported in literature, the mean absolute error has reduced by 68% for needle leaf and 20% for broadleaf canopies. Thus, the proposed DASF estimation approach outperforms the current one and can be used more reliably in DASF-related applications, such as vegetation monitoring of functional traits, dynamics, and radiation budget.
