Geometric Self-Calibration of YaoGan-13 Images Using Multiple Overlapping Images

Abstract

Geometric calibration is an important means of improving the absolute positioning accuracy of space-borne synthetic aperture radar imagery. The conventional calibration method is based on a calibration field, which is simple and convenient, but requires a great deal of manpower and material resources to obtain ground control points. Although newer cross-calibration methods do not require ground control points, calibration accuracy still depends on a periodically updated reference image. Accordingly, this study proposes a geometric self-calibration method based on the positioning consistency constraint of conjugate image points to provide rapid and accurate calibration of the YaoGan-13 satellite. The proposed method can accurately calibrate geometric parameters without requiring ground control points or high-precision reference images. To verify the absolute positioning accuracy obtained using the proposed self-calibration method, YaoGan-13 Stripmap images of multiple regions were collected and evaluated. The results indicate that high-accuracy absolute positioning can be achieved with a plane accuracy of 3.83 m or better for Stripmap data, without regarding elevation error. Compared to the conventional calibration method using high-accuracy control data, the difference between the two methods is only about 2.53 m, less than the 3-m resolution of the image, verifying the effectiveness of the proposed self-calibration method.

Field-free geometric calibration method for spaceborne SAR considering dilution of precision

“…The field-free geometric calibration model consists of range equations and Doppler equations. 17 The model compensates for the unknown system slant range error R s in the equation. The geometric calibration model is shown as…”

“…At least three images are required for field-free geometric calibration. 17 Out of 18 images, there are a total of 816 possible combinations to select three images for calibration.…”

“…At the same time, it is essential to mitigate the impact of elevation by ensuring a minimal difference in incidence angle between the reference image and the calibration image, which results in the imposition of stringent usage conditions. Zhang et al 17 used more than three images to establish a field-free geometric calibration model based on the positioning consistency constraint of conjugate image points to solve the geometric calibration parameters by the least squares method. This method can accurately solve the problem only when there are a sufficient number of images available.…”

Research on Integrated Static and Dynamic Geometric Calibration Technology for Optical Surveying and Mapping Satellites

“…After a satellite is launched into orbit, the optical components and mechanical structure of the sensor system may be changed or degraded due to the influence of launch vibration, solar radiation in orbit, and the impact of cosmic particles, which seriously affects the positioning accuracy of the target point (Wang, et al, 2014, Zhang, et al, 2019. In this part, a calibration model of the satellite camera included angle change value and the camera's interior elements is constructed.…”

Improvement of the spaceborne synthetic aperture radar stereo positioning accuracy without ground control points

“…Reference images are high-precision digital orthophoto maps and digital surface models of local areas obtained by aircraft, which make it difficult to meet the global calibration need for SAR satellites. The geometric self-calibration method (Zhang et al, 2019) and error source-based weight strategy (Jiao et al, 2018(Jiao et al, , 2020 were proposed to improve the stereo positioning accuracy; however, both methods still require at least three calibration images, which has certain limitations. Similar methods have been used to improve the accuracy of the interferometric SAR methods.…”