Optical imaging of space targets using ground-based or space-based telescopes is typically affected by complex noise. Due to the sparse features and limited data, the denoising performance of star images is often suboptimal. In this paper, we propose a lightweight zero-shot star image denoising framework featuring an improved 3-layer U-Net backbone, which can efficiently complete the denoising task without a complete dataset. This network extracts feature information through two pair of down-sampling and up-sampling layers, as well as several convolution modules. The spatial attention module is employed to focus on attention regions, enhancing the model efficiency and generalization ability. In the experiments conducted with real star images, the denoising pipeline primarily consists of three steps: image preprocessing, network training and inference. The results demonstrate that our method effectively removes noise from star images and outperforms existing techniques, facilitating the accurate detection and extraction of space targets in subsequent research.
For ocean remote sensing, target positioning over large areas of sea surface can be challenging, and traditional methods that rely on control points data may not be applicable in such cases. AIS data are commonly used as auxiliary data source of ocean remote sensing, which contains a wealth of attribute information of target. High-precision position information for a large number of targets is provided by the AIS equipped with differential GPS. AIS can be used as dynamic control points on the sea surface to contribute to target positioning in remote sensing image, meeting the on-orbit real-time positioning requirements of ocean remote sensing. This paper proposes a method for on-orbit target positioning and identification through the data fusion of optical image and AIS data. Firstly, the target position information provided by AIS is the broadcasted position over a period of time, while remote sensing image provide the instantaneous captured position. Therefore, it is necessary to calibrate the two types of data in terms of time and space. Then, the grid matching algorithm is used to establish the corresponding relationships between the same targets from the two different datasets, thereby achieving data fusion. Finally, target positioning is achieved over large areas of sea surface. In addition, the identification of target can also be facilitated by remote sensing image with the aid of AIS data, enabling precise positioning of abnormal target while obtaining their image information. In this paper, 5-meter resolution Jilin-1 satellite image and AIS data are used as data sources. The results show that, compared with the original data, the positioning error values calculated by this method are between 5-20 meters, with a reduction of over 70% in the RMSE value.
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