Jiang Weihao, Yu Anxi, Dong Zhen, Wang Qingsong
College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China.
Equipment Academy of the Rocket Force, Beijing 100085, China.
Sensors (Basel). 2016 Jun 25;16(7):973. doi: 10.3390/s16070973.
Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model.
随着合成孔径雷达（SAR）技术的发展，SAR图像越来越普遍。许多研究人员对地理定位模型进行了大量研究，但针对不同地形SAR图像几何校正的现有模型的研究却很少。为了解决地形问题，本文比较并描述了四种不同的模型：严格距离多普勒（RD）模型、有理多项式系数（RPC）模型、修正多项式（PM）模型和高程推导（EDM）模型。模型地理定位能力的比较结果表明，可以为特定地形的SAR图像确定合适的模型。获得了一个解决方案表，为用户推荐合适的模型。实验使用了三幅TerraSAR-X图像、两幅ALOS-PALSAR图像和一幅Envisat-ASAR图像，包括平坦地形和山地地形的SAR图像以及两幅大面积图像。计算并分析了不同地形SAR图像模型的地理定位精度。模型比较表明，RD模型准确但效率最低；因此，它不是实时应用的理想模型。RPC模型对于平坦地形SAR图像的几何校正足够准确且高效，其精度低于0.001像素。EDM模型适用于山地地形SAR图像的地理定位，其精度可达0.007像素。虽然PM模型产生的结果不如其他模型精确，但其效率极佳，其潜力不应被低估。对于大面积SAR图像的几何校正，EDM模型在一个像素范围内具有更高的精度，而RPC模型消耗的时间是EDM模型的三分之一。
