| 植被冠层光谱和叶片光谱的尺度转换 |
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| 引用本文： | 于颖,宋张亮,范文义,杨曦光.植被冠层光谱和叶片光谱的尺度转换[J].武汉大学学报(信息科学版),2018,43(10):1560. |
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| 作者姓名： | 于颖 宋张亮 范文义 杨曦光 |
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| 作者单位： | 1.东北林业大学林学院, 黑龙江 哈尔滨, 150040 |
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| 基金项目： | 国家自然科学基金31500518国家自然科学基金31500519 |
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| 摘 要： | 叶片光谱是估算植被生化参数的重要依据。然而，遥感影像获取的光谱为像元及冠层光谱，因此，在进行植被生化参数的遥感定量估算时，需将冠层光谱转化到叶片尺度。根据几何光学模型原理，推导出植被冠层光谱和叶片光谱的尺度转换函数，将冠层光谱转换到叶片尺度。首先，采用叶片光谱模拟模型PROSPECT模拟出叶片水平的光谱；其次，在几何光学模型4-scale模型中，通过改变叶片光谱和叶面积指数（leaf area index，LAI），模拟出不同叶片特征下的冠层光谱。最后，通过LAI建立两个查找表，一个是传感器观测到树冠光照面和背景光照面概率的查找表，另一个是多次散射因子M的查找表，从而实现冠层光谱和叶片光谱的转化。结果表明，利用4-scale模型能实现冠层光谱与叶片光谱的尺度转换，此方法有很好的适用性。
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| 关 键 词： | 高光谱遥感 PROSPECT模型 4-scale模型 叶面积指数LAI |
| 收稿时间： | 2017-09-13 |
Scale Conversion from Canopy Spectra to Leaf Spectra |
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| Affiliation: | 1.School of Forestry, Northeast Forestry University, Harbin 150040, China2.Key Laboratory of Saline-Alkali Vegetation Ecology Restoration(SAVER), Ministry of Education(Alkali Soil Natural Environmental Science Center(ASNESC), Northeast Forestry University), Harbin 150040, China |
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| Abstract: | Leaf spectrum is very important to estimate vegetation biochemical parameters. However, the spectrum obtained from remote sensing is pixel and canopy spectrum, therefore, it is necessary to transform the spectrum from canopy level to leaf level when estimating leaf biochemical parameters by remote sensing data. The scaling conversion function during downscales from pixel spectra, canopy spectra to leaf spectra was derived according to principles of geometrical optics model in this paper. First, PROSPECT model was used to simulate leaf spectra. Then, with the other parameters unchanged, the canopy spectra was simulated under different leaf area index(LAI) and leaf spectra by 4-scale model, and the relationship between leaf reflectance and sunlit canopy reflectance was found. Finally, two lookuping tables were established based on LAI to achieve transformation from canopy spectra to leaf spectra. One is used to describe the relations between the probability of observed sunlit canopy and observed illuminating background. The other is for scattering factor calculation. The result indicates that leaf spectra can be well converted from canopy spectra using 4-scale model. The proposed method is very effective and useful. |
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