起伏地形的高光谱遥感地气耦合辐射建模研究

邻近效应会影响高光谱遥感的定量化应用，而地气耦合辐射是邻近效应的重要组成部分。高光谱遥感数据多受地形背光和阴影的影响，不利于描述地物的光谱特性，并且地形的相互遮蔽使得辐射在大气、地表之间的耦合过程变得更加复杂。为了满足高光谱数据模拟快速性的要求，在深入分析辐射传输过程的基础上，利用邻近地物和目标地物的相对方位以及局地地形特征描述背景等效反射率，计算地气耦合辐射对传感器入瞳辐亮度的贡献，从而在起伏地形下实现了精确的地气耦合辐射建模。将此建模方法应用于高光谱遥感成像仿真，通过对实测图像的模拟，验证模型的有效性。结果表明，模拟图像与实测图像在视觉效果上具有较好的一致性;在地形起伏区域，仿真中采用改进后的地气耦合模型可提高模拟图像与实测图像的光谱相似度，同时在地形平坦区域保持了较高的仿真精度。

Study on the Modeling of Earth-Atmosphere Coupling over Rugged Scenes for Hyperspectral Remote Sensing

Adjacency effects may introduce errors in the quantitative applications of hyperspectral remote sensing, of which the significant item is the earth-atmosphere coupling radiance. However, the surrounding relief and shadow induce strong changes in hyperspectral images acquired from rugged terrain, which is not accurate to describe the spectral characteristics. Furthermore, the radiative coupling process between the earth and the atmosphere is more complex over the rugged scenes. In order to meet the requirements of real-time processing in data simulation, an equivalent reflectance of background was developed by taking into account the topography and the geometry between surroundings and targets based on the radiative transfer process. The contributions of the coupling to the signal at sensor level were then evaluated. This approach was integrated to the sensor-level radiance simulation model and then validated through simulating a set of actual radiance data. The results show that the visual effect of simulated images is consistent with that of observed images. It was also shown that the spectral similarity is improved over rugged scenes. In addition, the model precision is maintained at the same level over flat scenes.