State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China.
School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China.
Sensors (Basel). 2018 Nov 18;18(11):4023. doi: 10.3390/s18114023.
The Gaofen-3 (GF-3) satellite is the first C-band multi-polarization synthetic aperture radar (SAR) with the ability of high-accuracy mapping in China. However, the Ground Control Points (GCPs) are essential to ensure the accuracy of mapping for GF-3 SAR imagery at present. In this paper, we analyze the error sources that affect the geometric processing and propose a new block adjustment method without GCPs for GF-3 SAR imagery. Firstly, the geometric calibration of GF-3 image is carried out. Secondly, the rational polynomial coefficient (RPC) model is directly generated after the geometric calibration parameters compensation of each image. Finally, we solve the orientation parameters of the GF-3 images through DEM assisted planar block adjustment and conduct ortho-rectification. With two different imaging modes of GF-3 satellite, which include the QPSI and FS2, we carry out the block adjustment without GCPs. Experimental results of testing areas including Wuhan city and Hubei province in China show that the geometric mosaic accuracy and the absolute positioning accuracy of the orthophoto are better than one pixel, which has laid a good foundation for the application of GF-3 image in global high-accuracy mapping.
高分三号（GF-3）卫星是中国第一颗具有高精度测绘能力的 C 波段多极化合成孔径雷达（SAR）卫星。然而，目前地面控制点（GCPs）对于保证 GF-3 SAR 图像的测绘精度是必不可少的。本文分析了影响 GF-3 SAR 图像几何处理的误差源，并提出了一种新的无 GCP 的 GF-3 SAR 图像区域网平差方法。首先，对 GF-3 图像进行几何校正。其次，在对各图像的几何校正参数补偿后，直接生成有理多项式系数（RPC）模型。最后，通过 DEM 辅助的平面区域网平差解算 GF-3 图像的定向参数，并进行正射校正。利用 GF-3 卫星的两种不同成像模式，即 QPSI 和 FS2，进行了无 GCP 的区域网平差。对包括中国武汉市和湖北省在内的试验区的实验结果表明，正射影像的几何镶嵌精度和绝对定位精度优于 1 个像素，为 GF-3 图像在全球高精度测绘中的应用奠定了良好的基础。
