Improvement and Assessment of the Absolute Positioning Accuracy of Chinese High-Resolution SAR Satellites

Deng Deng,Zhao Zhao,Suo Suo,Zhang Zhang,Guo Guo,Cai Cai,Xu Xu

doi:10.3390/rs11121465

Abstract

In recent years, China has launched YaoGan-13 and GaoFen-3, high-resolution synthetic aperture radar (SAR) satellites that can acquire global high-resolution images. The absolute positioning accuracy of such satellites is important for mapping areas without ground reference points and for automated processing. However, satellites without geometric calibration have poor absolute positioning accuracy, greatly restricting their application (e.g., land resource surveys). Therefore, they cannot meet national demands for high-resolution SAR images with good geometric accuracy. Here, we propose a series of methods to improve the absolute positioning accuracy of YaoGan-13 and GaoFen-3, such as the multiple-image combined calibration strategy and geometric calibration model for a real continuously moving configuration, including consideration of atmospheric propagation delay. Using high-accuracy ground control data collected from different areas, the 2-D and 3-D absolute positioning accuracies of YaoGan-13 and GaoFen-3 were assessed after implementation of the improvement measures. Experimental results showed that, after calibration, the 2-D absolute positioning accuracy of YaoGan-13 and GaoFen-3 are improved from 43.86 m to 2.57 m and from 30.34 m to 4.29 m, respectively. In addition, the 3-D absolute positioning accuracies of YaoGan-13 in plane and elevation are 3.21 m and 2.22 m, respectively. Improving the absolute positioning accuracy of these satellites could broaden the scope of their potential applications in the future.

Highlights

In China, there is considerable demand for high-resolution synthetic aperture radar (SAR) images for use in activities such as mapping and resource monitoring
The launches of YaoGan-13 and GaoFen-3 have attracted considerable attention from international researchers. To inform these international researchers about YaoGan-13 and GaoFen-3, this paper proposes a series of methods for improving the absolute positioning accuracy of these two satellites, such as the multiple-image combined calibration strategy and geometric calibration model for a real continuously moving configuration, including consideration of atmospheric propagation delay
It can be drawn that the internal electronic delay of the instrument has become the most important factor affecting the correct localization of YaoGan-13 and GaoFen-3 images

Summary

Introduction

In China, there is considerable demand for high-resolution synthetic aperture radar (SAR) images for use in activities such as mapping and resource monitoring. To meet this demand, China launched two satellites, YaoGan-13 and GaoFen-3, and the resolution of their images has been upgraded from the meter to the submeter level [1,2]. China launched two satellites, YaoGan-13 and GaoFen-3, and the resolution of their images has been upgraded from the meter to the submeter level [1,2] This means that China can acquire global high-resolution SAR images using YaoGan-13 and GaoFen-3. The spatial resolution varies from 1 to 500 m, and the swath varies from 10 to 650 km

Results

Discussion

Conclusion