Dr. Ting Li Profile

Dr. Ting Li

at China Academy of Space Technology

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 30 April 2024 Paper

Full-field-of-view image quality analysis based on residual distribution of drift angle in agile satellite

Wangjia Liu, Ting Li, Jing Pan, Zixi Guo, Jing Cao

Proceedings Volume 13157, 1315714 (2024) https://doi.org/10.1117/12.3018438

KEYWORDS: Satellites, Modulation transfer functions, Image quality, Satellite imaging, Imaging systems, Cameras, Active imaging, Image processing, Remote sensing, Matrices

Read Abstract +

In recent years, there has been a significant focus on using agile modes in high-resolution optical satellites. These modes, such as active push-broom, multi-angle stereo imaging, and non-along-track imaging, take advantage of the satellite's maneuverability to improve the balance between spatial resolution and time resolution, thus enhancing imaging efficiency. However, compared to traditional passive push-broom imaging, these methods can result in a decrease in image quality. For instance, a drift angle can cause a shift in the image's nadir direction, leading to a reduction in the modulation transfer function (MTF). While satellites have measures to correct for drift angles, the impact of drift angle on wide-field optical remote sensing satellite imaging cannot be ignored, especially during active push-broom imaging processes that involve large attitude maneuvers and low precision in satellite attitude control. The residual effect of correcting for drift angle varies across different points in the full field of view under different non-along-track imaging conditions. Generally speaking, the magnitude of residuals is directly proportional to the angle of the track and the proximity to the edge of the field of view. A quantitative analysis model has been developed to evaluate the imaging quality degradation under various non-along-track conditions for different parameter designs. This model takes into account the distribution of residuals after correcting for the drift angle, which causes an uneven decrease in MTF across the field of view. It enables the selection of optimal parameter combinations for multiple imaging parameters and task planning, ensuring that the imaging quality in the target area meets user requirements. Using the orbital elements and a set of angles and starting point latitude and longitude between 0° and 330° spaced 30° apart for non-along-track imaging tasks, 13 unequally spaced sampling points in the full field of view were selected to simulate the residual drift angle under typical non-along-track imaging conditions. The residual drift angle distribution map was drawn in each image and further, the MTF (Modulation Transfer Function) map was calculated. These maps represent the distribution of image quality within the images and validate the effectiveness of the quantitative analysis model. The analysis results are valuable for ensuring the imaging quality of high-resolution optical satellites during agile imaging and can be further extended to develop image-quality-oriented agile mission planning methods and other applications.