Space Camera Vibration Parameters Detection And Blurred Image Restoration

During on-orbit working process of the remote sensing satellite, the gesture of the satellite platform will be disturbed under the influence of external factors, such as sunlight pressure, gravity gradient, spatial micrometeorites debris, etc., or internal factors, such as, solar panels, reaction wheels, the mechanical and thermal effects of other moving parts, etc. The disturbance shall be passed to the remote sensor platform, assumed as phenomena of the platform vibrations. During the integration of space camera imaging process, the vibrations will lead to relative movement of the scene projection, thereby reducing the image quality. With the progress of the remote sensing optical system’s designing and manufacturing level and the enhancement of the optical imaging device’s performance, the angle resolution of the spatial camera has continuous improvement, also lead the camera more sensitive to vibrations. Vibrations start to become an important factor affecting the quality of high-resolution remote sensing device. Detecting space camera vibration parameters is fairly significant to research of the vibration law of the satellite platform and enhancement of the remote sensing performance. But also provides data basement for the vibration suppression and restoration of the degraded image. The main work of this paper is as follows:From the optical system’s modulation transfer function, we will analyse the influence of vibrations to the MTF, derive the formulas between MTF and vibration parameters, and with simulation experiment show the vibration influence of the vibration amplitude, frequency and other parameters to TDICCD image quality visually by using evaluation parameters.For focal plane mechanical splice structure TDICCD scanning camera, we propose a method for detecting vibration parameters, by utilizing spliced region which imaging the same scene repeatedly. Reaching the purpose of no additional facilities, using only the camera self structure to accurately measure the parameters of camera vibrations. For more application, based on a rolling shutter CMOS image sensor autocorrelation imaging, we propose a vibration parameters detecting method, which can be preferably used at both scanning camera and staring camera, achieving the purpose of utilizing image sequences of low frame rate to detect high frequency vibrations, greatly reducing the image transmission and processing pressure, making the detection algorithm satellite embedded transplant possible.According to the sensor imaging principle, presents an analog imaging methods which simulate TDICCD and rolling shutter CMOS imaging by using global shutter camera. Based on the method, we design a checking experiment to validate the vibration parameters detecting methods, and then construct experimental platform, design experimental parameters, prove that both of the two vibration parameter detection methods to be true. Validation results showed that both detection methods are accurate: for detection method based on focal plane mechanical splice structure TDICCD, the cycle detecting relative error is less than 2%, the amplitude detecting absolute error is less than 2 pixel; for detection method based on plane-array CMOS autocorrelation imaging, the cycle detecting relative error is less than 1%, the amplitude detecting absolute error is less than 1 pixel.Through the vibration detection method validation experiments, we get the parameters of the detected vibration, then restore the vibration degraded image. Presents a vibration point spread function discretization method. For any vibration that known function of movement, through this pixel-level discrete interpolation algorithm can quickly calculate the point spread function. Restore the blurred image by utilizing the discrete point spread function and evaluate the image quality objectively by using evaluation parameters that before and after the restoration, the evaluation results show that the restoration effect is obvious, indirect prove the correctness of two proposed vibration parameter detection method.