Wavelength Extension of the Optimized Asymmetric-Order Vegetation Isoline Equation to Cover the Range from Visible to Near-Infrared
Wavelength Extension of the Optimized Asymmetric-Order Vegetation Isoline Equation to Cover the Range from Visible to Near-Infrared
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DOI：
10.3390/rs14092289
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发表时间：
2022-05
期刊：
影响因子：
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通讯作者：
Munenori Miura;K. Obata;H. Yoshioka
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文献类型：
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作者：
Munenori Miura;K. Obata;H. Yoshioka
植被等值线方程描述了不同波长的两个反射率之间的解析关系。它们的应用范围从生物物理参数的检索到光谱植被指数传感器间关系的推导。在迄今为止介绍的三种植被等值线方程中，优化的非对称阶植被等值线方程是最新的，并且被认为是最精确的。然而，仅对分别固定在655 nm和865 nm的红色和近红外（NIR）波段的波长对进行了准确度评估。本研究的目的是扩展这种波长限制。因此，在400至1200 nm的更宽波长范围内进行了准确度评估。优化的非对称顺序植被等值线方程被证实，以证明最高的精度之间的三个等值线的所有调查的波长对。第二个最好的方程，不包括优化因子的非对称阶等值线方程，并不上级最不精确的方程（即，一阶等值线方程）。当两个波长的反射率相似时，这种趋势突出。相比之下，优化的非对称顺序植被等值线在整个研究中表现出稳定的性能。在优化的非对称阶等值线方程中引入一个单一的因子，可以有效地减少所有波长组合的等值线误差。
Vegetation isoline equations describe analytical relationships between two reflectances of different wavelengths. Their applications range from retrievals of biophysical parameters to the derivation of the inter-sensor relationships of spectral vegetation indexes. Among the three variants of vegetation isoline equations introduced thus far, the optimized asymmetric-order vegetation isoline equation is the newest and is known to be the most accurate. This accuracy assessment, however, has been performed only for the wavelength pair of red and near-infrared (NIR) bands fixed at ∼655 nm and ∼865 nm, respectively. The objective of this study is to extend this wavelength limitation. An accuracy assessment was therefore performed over a wider range of wavelengths, from 400 to 1200 nm. The optimized asymmetric-order vegetation isoline equation was confirmed to demonstrate the highest accuracy among the three isolines for all the investigated wavelength pairs. The second-best equation, the asymmetric-order isoline equation, which does not include an optimization factor, was not superior to the least-accurate equation (i.e., the first-order isoline equation) in some cases. This tendency was prominent when the reflectances of the two wavelengths were similar. By contrast, the optimized asymmetric-order vegetation isoline showed stable performance throughout this study. A single factor introduced into the optimized asymmetric-order isoline equation was concluded to effectively reduce errors in the isoline for all the wavelength combinations examined in this study.