利用DEM进行SAR图像模拟及地形辐射校正

Simulating SAR Images and Correcting Terrain Radiation Using DEM

在山区获取地面控制点比较困难,运用模拟SAR进行配准、校正,具有较大的优势。本文在分析SAR成像几何结构及ALOS PALSAR卫星轨道参数特征的基础上,运用RD定位模型对DEM的每个网格点进行雷达成像点的位置计算,模拟SAR图像,并提取当地入射角、投影角及规则化因子等;模拟出的SAR图像与真实SAR图像纹理吻合,有利于控制点的自动配准。在此基础上对ALOS PALSAR进行编码,构建基于规则化因子及入射角的地形辐射校正模型,消除面积效应及地形起伏造成的畸变问题,从结果中分析,校正后的图像明暗差异明显减少,这对雷达定量反演研究具有一定的现实意义。

The simulated SAR image is beneficial to the automatic registration of the control points and image correction,especially in the mountains, where it is very difficult to get the ground control point. Based on the analysis of SAR imaging geometry and characteristics of ALOS PALSAR satellite orbit parameters, the range doppler （RD）geo-location model is used to calculate the position of the radar imaging point for each grid point of the DEM. The SAR image is simulated, the local incidence angle, projection angle,regularization factor are extracted. The simulated SAR image coincides with the real SAR image texture, which is beneficial to the automatic registration of the control points. And the terrain radiation correction model based on the regularization factor and angle of incidence is constructed to eliminate the distortion caused by the area effect and terrain undulation. From the analysis results, the difference of the brightness and darkness of the image after correction is obviously reduced. It has certain practical significance to radar quantitative inversion research.