Geolocation Accuracy Improvement of Multiobserved GF-3 Spaceborne SAR Imagery

As the first C-band full-polarization spaceborne synthetic aperture radar (SAR) satellite in China, Gaofen-3 (GF-3) is of great significance in scientific research and economic development. Thanks to the advantage of all-weather and all-day observation, spaceborne SAR imagery is widely used in digital elevation model (DEM) generation, target tracking, and so on. And, all these applications are based on the high 3-D geolocation accuracy of SAR imagery. Therefore, a new slant range error update model and an error-source-based weight strategy which can effectively improve the 3-D geolocation accuracy of multiobserved data set from GF-3 satellite are proposed in this letter. The slant range error update model is proposed to improve the 3-D geolocation accuracy using the virtual control information in height direction. At the same time, an error-source-based weight strategy is introduced as an appendant to the multiobservation block adjustment model based on the rational function model (RFM). The experimental results demonstrate that our proposed method can achieve a much higher 3-D geolocation accuracy than the traditional methods.