地形引起的雷达辐射畸变及其校正

Terrain Induced SAR Radiometric Distortions and Their Correction

合成孔径雷达影像由于其侧视特点 ,存在着严重的地形引起的几何畸变及辐射畸变。辐射畸变不仅对 SAR辐射标定造成困难 ,而且严重影响了影像分类、土壤湿度信息提取、森林蓄积量信息提取等应用。本文将辐射畸变归结为面积效应和局部入射角效应 ,推导了散射面积归一化因子 ,以消除辐射畸变的面积效应。提出了一种以局部入射角的线性函数表达的后向散射模型 ,在此基础上 ,给出了消除局部入射角效应的校正函数。最后 ,以RADARSAT

Synthetic Aperture Radar images suffer severely geometric and radiometric distortions caused by terrain undulation because of its side looking characteristic. The radiometric distortions not only bring on difficulties to precise radiometric calibration, but also affect the SAR imagery application, including image classification, soil moisture information and forest biomass information extraction from SAR backscatter coefficients. The terrain induced radiometric distortions are categorized two: one is pixel scattering area effect, the other is local incidence angle effect. To correct the pixel scattering area effect, the pixel scattering area normalization factor is developed. To correct the local incidence angle effect, a linear scattering model between the backscatter coefficient and local incidence angle is proposed. On the basis of them, the radiometric distortion correction algorithm is developed. At last, a test of SAR radiometric distortions correction using RADARSAT SGF data is performed and analyzed.