Modeling directional brightness temperature over a maize canopy in row structure
Modeling directional brightness temperature over a maize canopy in row structure
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DOI：
10.1109/igarss.2003.1294765
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发表时间：
2003-07
期刊：
影响因子：
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通讯作者：
Tao Yu;G. Tian;Yonghong Lv;M. Legrand;Xingfa Gu;J. Hanocq;R. Bosseno
中科院分区：
文献类型：
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作者：
Tao Yu;G. Tian;Yonghong Lv;M. Legrand;Xingfa Gu;J. Hanocq;R. Bosseno
利用大口径热红外相机拍摄的玉米冠层图像，对行结构作物的方向亮温变化进行了模拟研究。该模型假设DBT是组件的亮度温度和它们的方向分数的函数。冠层有三个亮温分量：日照土壤、遮荫土壤和植被，每个分量都有一个唯一的温度值。组分分数在现场的看法取决于太阳视图的几何形状和植物行内和之间的间隙的分布。为了描述冠层的几何特征，采用了一个具有矩形截面的多孔植物篱系统，用Nilson函数描述了林隙率的方向变化。该模型演示了DBT的方向变化作为太阳观察几何形状和冠层几何结构以及组件亮度温度的函数。模拟结果表明，在正午时分，DBT极图上存在明显的行向热条带，热斑沿着太阳方向出现。模型对输入参数的灵敏度进行了测试。还进行了进一步的验证分析，表明模拟的DBT与现场观察结果密切一致。
A modeling study on the variations of directional brightness temperature (DBT) for row-structure crops was carried out with the help of the images captured by a large aperture thermal infrared camera over a maize canopy. The model assumes that the DBT is a function of component brightness temperatures and their directional fractions. The canopy has three brightness temperature components: sunlit soil, shaded soil and vegetation, each component has a unique temperature value. Component fractions in the scene of view depend on sun-view geometry and the distributions of gaps within and between plant rows. To describe canopy geometrical features, a system of porous hedgerows with rectangle cross-section has been used; the directional variations of gap fraction are described by Nilson function. The model demonstrates directional variations of DBT as a function of sun-viewing geometry and canopy geometrical structure as well as component brightness temperatures. In the simulation of DBT over a middle dense canopy near the noontime, the results reveal an evident row-direction-oriented hot stripe in the DBT polar map, where appeared the hot spot along the sun direction. The sensitivities of the model to the input parameters have been tested. Further validation analysis has also been conducted which demonstrates modeled DBT agreeing closely with field observations.