On February 7th, invited by the State Key Laboratory of Geodesy and Earth's Dynamics, ZHANG Yunjun, a researcher from Aerospace Information Research Institute,Chinese Academy of Sciences, visited the laboratory and presented a report titled "Geometric Positioning of C/L-Band Spaceborne SAR and Its Implications for SAR Image Registration in the Era of Big Data". The meeting was presided over by JIANG Liming, a researcher from APM, and attended by researchers YUAN Yunbin and ZHANG Baocheng, associate researcher HUANG Ronggang, and other teachers and students both online and offline.
The report mainly introduced one of ZHANG Yunjun's works - the analysis of influencing factors of SAR geometric positioning errors and the model-driven image registration method. First, big data statistics were used to analyze the sources of geometric positioning errors of C and L-band SAR satellites, including ionospheric delay, tropospheric delay, and solid tide motion. Secondly, the report focused on explaining the method of SAR image registration using external models to correct atmospheric delay errors, solid tide motion, and surface motion (MAGIC). This method improved the relative geometric positioning error accuracy of C-band Sentinel-1 and L-band ALOS-2 data by four times.
After the report, the participating teachers and students had a lively discussion with ZHANG Yunjun on key technical issues such as geophysical models in GNSS, SAR precise positioning, and InSAR deformation inversion.