Simulated impact of sensor field of view and distance on field measurements of bidirectional reflectance factors for row crops
Simulated impact of sensor field of view and distance on field measurements of bidirectional reflectance factors for row crops
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模拟传感器视场和距离对中耕作物双向反射系数现场测量的影响
DOI：
10.1016/j.rse.2014.09.011
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发表时间：
2015
影响因子：
13.5
通讯作者：
Huang Jianxi
中科院分区：
文献类型：
--
作者：
Zhao Feng;Li Yuguang;Dai Xu;Verhoef Wout;Guo Yiqing;Shang Hong;Gu Xingfa;Huang Yanbo;Yu Tao;Huang Jianxi
众所周知，自然表面表现出取决于表面特性的各向异性反射特性。地面双向反射因子（BRF）的光谱测量为我们提供了一种捕获观测表面方向特性的方法。采用不同视场的光谱辐射计在不同安装条件下测量作物反射率。传感器视场和与目标的距离的影响和不确定性很少被考虑。这个问题可以与异质行作物的特征反射率相结合。针对自然环境下作物反射率难以精确获得的问题，提出了一种计算机模拟方法，研究了传感器视场和距离对作物反射率的影响。建立了一个蒙特卡罗模型，结合联合收割机的光子扩散方法和重量减少的概念，发展了加权光子扩散（WPS）模型，模拟辐射传输的建筑真实感檐篷。Monte Carlo模型与两个现场BRF测量和RAMI在线模型（ROMC）的比较显示出良好的一致性。BRFs，然后模拟一系列的传感器FOV和距离的组合，并与参考值（在无穷远的距离）为两个典型的行冠层场景进行比较。具有有限FOV和距目标的距离的传感器近似反射率各向异性，并产生FOV上的平均值。此外，传感器的透视投影导致传感器FOV与理想方向观测值成比例失真。研究发现，尽管存在这些因素，但只要传感器视场和距离的合理组合，就可以在地面上获得具有可容忍偏差的BRF，但热点方向及其周围方向除外，并对传感器视场和距离的选择提出了建议，以减少行播作物田间BRF测量中与真实的角度特征的偏差。
It is well established that a natural surface exhibits anisotropic reflectance properties that depend on the characteristics of the surface. Spectral measurements of the bidirectional reflectance factor (BRF) at ground level provide us a method to capture the directional characteristics of the observed surface. Various spectro-radiometers with different field of views (FOVs) were used under different mounting conditions to measure crop reflectance. The impact and uncertainty of sensor FOV and distance from the target have rarely been considered. The issue can be compounded with the characteristic reflectance of heterogeneous row crops. Because of the difficulty of accurately obtaining field measurements of crop reflectance under natural environments, a method of computer simulation was proposed to study the impact of sensor FOV and distance on field measured BRFs. A Monte Carlo model was built to combine the photon spread method and the weight reduction concept to develop the weighted photon spread (WPS) model to simulate radiation transfer in architecturally realistic canopies. Comparisons of the Monte Carlo model with both field BRF measurements and the RAMI Online Model Checker (ROMC) showed good agreement. BRFs were then simulated for a range of sensor FOV and distance combinations and compared with the reference values (distance at infinity) for two typical row canopy scenes. Sensors with a finite FOV and distance from the target approximate the reflectance anisotropy and yield average values over FOV. Moreover, the perspective projection of the sensor causes a proportional distortion in the sensor FOV from the ideal directional observations. Though such factors inducing the measurement error exist, it was found that the BRF can be obtained with a tolerable bias on ground level with a proper combination of sensor FOV and distance, except for the hotspot direction and the directions around it. Recommendations for the choice of sensor FOV and distance are also made to reduce the bias from the real angular signatures in field BRF measurement for row crops.
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传感器足迹对中耕作物冠层定向亮度温度测量的影响
影响因子：
13.5
作者：
Ren Hua-zhong;Yan Guang-Jian;Liu Rong-Yuan;Nerry Francoise;Li Zhao-Liang;Hu Rong-Hai
通讯作者：
Hu Rong-Hai
影响因子：
2.1
作者：
C. Daughtry;V. Vanderbilt;V. J. Pollara
通讯作者：
C. Daughtry;V. Vanderbilt;V. J. Pollara
影响因子：
3.1
作者：
G. Katul;J. Albertson;C. Hsieh;P. Conklin;J. Sigmon;M. Parlange;K. Knoerr
通讯作者：
G. Katul;J. Albertson;C. Hsieh;P. Conklin;J. Sigmon;M. Parlange;K. Knoerr
DOI：
10.1117/12.560962
发表时间：
2004-10
期刊：
--
影响因子：
--
作者：
M. Cutter
通讯作者：
M. Cutter
影响因子：
3.4
作者：
D. Deering;T. Eck
通讯作者：
D. Deering;T. Eck