Brightness gradients correction in airborne hyperspectral data by using empirical BRDF model
Brightness gradients correction in airborne hyperspectral data by using empirical BRDF model
复制标题
使用经验 BRDF 模型对机载高光谱数据进行亮度梯度校正
DOI：
10.4287/jsprs.46.4_55
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Kazuyoshi Takahashi
中科院分区：
文献类型：
--
作者：
T. Suhama;A. Rikimaru;Kazuyoshi Takahashi
机载高光谱传感器获取的表观反射率数据通常会受到地表介质双向反射分布函数（BRDF）的影响。机载高光谱传感器数据的预处理应包括对可能存在的亮度梯度进行校正，以测量表面介质的特征，对于像机载高光谱传感器这样的线阵扫描仪，亮度梯度主要发生在跨航迹方向上，并且与传感器的视角有关。然而，当用小飞机进行观测时，高光谱传感器的姿态在3个轴方向上变化，例如滚动、俯仰和偏航。因此，为了以足够的精度校正亮度梯度，不仅需要考虑跨轨道方向，还需要考虑沿机架方向。利用GPS/IMU测量的高光谱传感器姿态信息对BRDF进行高精度模拟是必不可少的，本文研究了利用两个或多个高光谱数据的重叠图像进行BRDF模拟的经验方法。所提出的技术能够估计的最低点反射率值，而无需任何额外的现场测量和估计的最低点反射率值可以用于任何后续的定性和定量分析。
In general, apparent reflectance data obtained by airborne hyperspectral sensor are affected by Bidirectional Reflectance Distribution Function (BRDF) of surface medium. A complete preprocessing of airborne hyperspectral sensor data should include the correction of a possible brightness gradient for measuring the feature of surface medium.For a line scanner like airborne hyperspectral sensor, the brightness gradients mainly occur in across-track direction and depend on the sensor's view angle. However, when the observations are done with the small planes, hyperspectral sensor attitude changes in the 3 axes directions, such as a rolling, pitching, and yawing. Therefore, in order to correct brightness gradient with sufficient accuracy, it is necessary to take into consideration not only the across-track direction but the alongt-rack direction also. A Highly precise simulation of BRDF using hyperspectral sensor attitude information measured by GPS/IMU is indispensable.This research examines the technique of conducting the simulation of the BRDF with the empirical approach using the lapped images of two or more hyperspectral data. The proposed technique enables the estimation of the nadir reflectance value without any additional field measurements and the estimated nadir reflectance value can be used for any subsequent qualitative and quantitative analysis.