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The novel rotating synthetic aperture imaging system has the advantages of short processing cycle, light weight, low cost, and convenient transport, which is a potential development direction for future optical satellite payloads with ultra-large aperture. However, influenced by the coupling effects of the rectangular primary mirror, rotating imaging, and link perturbation, images from this system may have unique spatial and temporal variability with resolution anisotropy, resulting in the dynamics and weak features of targets. The insufficient recognition of system characteristics seriously restricts the application ability of corresponding target interpretation methods. To address this problem, we start with the analysis of system imaging characteristics and target interpretation mechanisms. Considering calculating texture, grayscale, and edge feature parameters in evaluation regions of different sizes, we propose a degradation assessment method based on multi-scale feature characterization. Then, combined with the theoretical calculation and practical target detection experiments, the influence of crucial parameters such as the aspect ratio and rotation angle of the primary mirror on the target interpretation capability is analyzed. The results will provide guidance for the integrated design and optimization of optical imaging systems and intelligent image processing methods. • A degradation assessment method based on multi-scale feature characterization is proposed. • The effect of rotating synthetic aperture system on image target characteristic degradation is analyzed. • The impacts of key system parameters on target detection performance are analyzed. [ABSTRACT FROM AUTHOR]

Abstract Inverse synthetic aperture imaging lidar is a new active imaging system, which can offer a finer azimuth resolution than that achieved in conventional SAR system and obtain vivid images close to the optical photos. Firstly, the principle of the inverse synthetic aperture techniques is described. Secondly, after analyzing the data of the inverse synthetic aperture imaging lidar, the mathematic model of the data is given. Thirdly, a method, combined with "CLEAN" techniques, is proposed for inverse synthetic aperture imaging lidar processing, which is based on the analysis of data's time-frequency character. The presented method uses the second-order phase of the data in azimuth, estimates the instantaneous Doppler spectrum and obtains the instantaneous images in the range and the instantaneous Doppler domains, which can avoid the defocusing of the images using the range Doppler algorithm and improve the imaging quality. Finally, the data processing of the real data proves the validity of the given method. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) step parallel confocal image processing algorithm for synthetic aperture imaging ladar (SAIL) is proposed. The feature of the algorithm is the collected data are confocal imaged in space domain by 2D Fourier transform. The collected data are first expressed by separation of variables and time-domain data are translated into a spatial coordinate expression suitable for space optical conversion, compensated with an azimuth quadratic phase and then imaged in space domain by 2D Fourier transform. Functions of the algorithm for SAIL with rectangular apertures is described and analyzed in terms of continuous variables and functions. Then the position of the imaging point is given. The technique is a new, one-step confocal imaging method for ladar echo signal. The confocal image processing is simplified and the imaging time is shortened. The requirement of a ladar image processing system is also reduced. It has a significant advantage in the data processing of synthetic-aperture ladar target echo confocal imaging. [ABSTRACT FROM AUTHOR]