Hybrid Geometric Calibration Method for Multi-Platform Spaceborne Sar Image With Sparse GCPS

Abstract

ABSTRACT:Geometric calibration is able to provide high-accuracy geometric coordinates of spaceborne SAR image through accurate geometric parameters in the Range-Doppler model by ground control points (GCPs). However, it is very difficult to obtain GCPs that covering large-scale areas, especially in the mountainous regions. In addition, the traditional calibration method is only used for single platform SAR images and can't support the hybrid geometric calibration for multi-platform images. To solve the above problems, a hybrid geometric calibration method for multi-platform spaceborne SAR images with sparse GCPs is proposed in this paper. First, we calibrate the master image that contains GCPs. Secondly, the point tracking algorithm is used to obtain the tie points (TPs) between the master and slave images. Finally, we calibrate the slave images using TPs as the GCPs. We take the Beijing-TianjinHebei region as an example to study SAR image hybrid geometric calibration method using 3 TerraSAR-X images, 3 TanDEM-X images and 5 GF-3 images covering more than 235 kilometers in the north-south direction. Geometric calibration of all images is completed using only 5 GCPs. The GPS data extracted from GNSS receiver are used to assess the plane accuracy after calibration. The results after geometric calibration with sparse GCPs show that the geometric positioning accuracy is 3m for TSX/TDX images and 7.5m for GF-3 images.

Modeling the Optimal Baseline for a Spaceborne Bistatic SAR System to Generate DEMs

“…In other words, the estimation error of baseline inclination will be propagated the height measurement with the greater multiple. Regarding spaceborne SAR systems, due to the azimuthal clock-timing error, it is generally necessary to set ground control points, such as manually placed corner reflectors, to correct the abovementioned errors accurately [17][18][19][20]. Equation (10) represents the height measurement uncertainty associated with the interferometric phase error, which is mainly caused by the absolute phase offset and several decorrelation factors.…”

“…Thus, the absolute value of the terrain slope angle will be used to analyze the distribution of the topographic gradient. Then, the average slope angle of the complex terrain can be obtained and the optimal baseline range can be further calculated by Equations (18) and (19). ISPRS Int.…”

An Improved Independent Parameter Decomposition Method for Gaofen-3 Surveying and Mapping Calibration

“…Geometric calibration steps improve the plane positioning accuracy of SAR images by calibrating the geometric parameters, while interferometric calibration technologies improve the vertical accuracy of the interferometric results by calibrating the acquired interferometric parameters [13,14]; together, these calibration steps can be used to determine the accuracy level of a global DEM. At present, many research teams in China and globally have published geometric and interferometric calibration methods that are applicable for mainstream SAR satellites [9,13,15].…”

“…In 2018, a sparse-control multiplatform geometric calibration method was proposed for TerraSAR-X/TanDEM-X and GF-3 images. The geometric positioning accuracy of the TerraSAR-X/TanDEM-X images found using this method was better than 3 m, while that of the GF-3 images was better than 7.5 m following calibration [15]. In 2020, a wide-area joint geometric calibration method was proposed for GF-3 SAR images, and the positioning error of the calibrated SAR images was better than 9 m [20].…”

“…LÜ Guannan, Tang Xinming, Ai Bo [15] A sparse-control multiplatform geometric calibration method was proposed for Ter-raSAR-X/TanDEM-X and GF-3 images. The geometric positioning accuracy of the Ter-raSAR-X/TanDEM-X images found using this method was better than 3 m, while that of the GF-3 images was better than 7.5 m following calibration.…”