空间相机振动参数检测及降质图像复原

发布时间：2018-11-09 11:59

【摘要】：遥感卫星在轨工作期间,在太阳光压、地球引力梯度、空间微小陨石碎片等外部因素,及反作用轮、太阳帆板和其他运动部件的机械与热效应等内部因素的影响下,卫星平台的空间姿态会受到扰动,传递到遥感器平台,表现为平台的振动现象,这会导致空间相机成像过程中,景物在像面的投影产生相对移动,从而降低图像质量。随着遥感器光学系统设计及制造水平的进步和光学成像器件性能指标的提升,空间相机角分辨率在不断的提高,导致相机对振动也越来越敏感,振动开始成为影响高分辨率遥感器成像质量的重要因素。检测空间相机振动参数,对研究卫星平台振动规律,提升遥感器性能具有重要意义,也为振动抑制及降质图像复原提供了数据基础。论文的主要研究工作如下:从光学系统调制传递函数出发,分析了振动对于MTF的影响,推导了MTF和振动参数间的计算公式,并通过仿真实验,使用评价参数直观地展现了振动幅度、振动频率和积分级数等参数对于TDICCD成像质量的影响。针对焦平面为机械拼接结构的TDICCD推扫相机,提出了一种基于拼接区域对同一景物重复成像的振动检测方法,达到了不增加额外设备,仅利用相机自身结构精确测量相机振动参数的目的;同时为了提高检测方法的适用性,基于卷帘快门CMOS图像传感器自相关成像,提出了一种在推扫相机和凝视相机上均能有较好应用的振动参数检测方法,实现了利用低帧频图像序列检测高频振动的目的,大幅度降低了检测算法的数据传输及处理压力,为检测算法的星上嵌入式实现提供了可能。根据传感器成像原理,提出了一种利用全局快门相机模拟TDICCD和卷帘快门CMOS成像的方法。基于该方法设计了振动参数检测方法验证实验,并搭建实验平台、设计实验参数,分别对本文提出的两种振动参数检测方法进行验证实验。实验结果表明两种检测方法均有较好的检测精度:对于基于机械拼接结构TDICCD相机的振动参数检测方法周期检测相对误差小于2%,振幅检测绝对误差小于2个像元;对于基于面阵CMOS自相关成像的振动参数检测方法,周期相对误差小于1%,振幅绝对误差小于1个像元。根据振动检测方法验证实验中检测到的振动参数,对振动降质图像进行复原。提出一种振动点扩散函数离散化方法,对任意已知运动函数的振动,通过这种像素级插值离散化算法,均可快速计算其点扩散函数。利用得到的离散化点扩散函数对降质图像进行逐行复原,并使用评价参数客观评价复原前后图像质量,评价结果表明复原效果明显,证明了本文提出的两种振动参数检测方法的正确性。
[Abstract]:During the operation of the remote sensing satellite in orbit, it was affected by external factors such as solar pressure, gravity gradient of the earth, small space meteorite debris, and mechanical and thermal effects of reaction wheels, solar panels and other moving parts. The space attitude of the satellite platform will be disturbed and transmitted to the remote sensor platform, which will show the vibration phenomenon of the platform, which will lead to the relative movement of the scene projection on the image plane during the imaging process of the space camera, thus reducing the image quality. With the development of optical system design and manufacture of remote sensor and the improvement of optical imaging device performance index, the angular resolution of space camera is improving continuously, which makes the camera more and more sensitive to vibration. Vibration has become an important factor affecting the imaging quality of high resolution remote sensor. Detecting the vibration parameters of space camera is of great significance for studying the vibration law of satellite platform and improving the performance of remote sensor. It also provides a data basis for vibration suppression and restoration of degraded image. The main work of this paper is as follows: based on the modulation transfer function of optical system, the effect of vibration on MTF is analyzed, the formula between MTF and vibration parameters is deduced, and the simulation experiment is carried out. The effects of vibration amplitude, vibration frequency and integral series on TDICCD imaging quality are demonstrated intuitively by using evaluation parameters. Aiming at the TDICCD push-sweep camera with focal plane as mechanical splicing structure, a vibration detection method based on splicing area to duplicate imaging of the same scene is proposed, and no additional equipment is added. The purpose of measuring the camera vibration parameters accurately only by using the camera's own structure; At the same time, in order to improve the applicability of the detection method, based on the autocorrelation imaging of the shutter CMOS image sensor, a vibration parameter detection method is proposed, which can be applied to both the push-sweep camera and the staring camera. The purpose of detecting high frequency vibration by using low frame frequency image sequence is realized, and the data transmission and processing pressure of the detection algorithm is greatly reduced, which provides the possibility for the embedded realization of the detection algorithm on board. According to the principle of sensor imaging, a method of simulating TDICCD and shutter CMOS imaging by using global shutter camera is proposed. Based on this method, the validation experiment of vibration parameter detection method is designed, and the experimental platform is built, and the experimental parameters are designed. The two vibration parameter detection methods proposed in this paper are verified. The experimental results show that the two methods have good detection accuracy: for the vibration parameter detection method based on mechanical splicing structure TDICCD camera, the relative error is less than 2 and the absolute error of amplitude detection is less than 2 pixels; For the vibration parameter detection method based on plane array CMOS autocorrelation imaging, the relative error of period is less than 1 and the absolute error of amplitude is less than 1 pixel. According to the vibration detection method to verify the vibration parameters detected in the experiment, the vibration degradation image is restored. A method for discretization of vibration point diffusion function is proposed. The pixel level interpolation discretization algorithm can be used to calculate the point diffusion function of any known motion function. The discrete point diffusion function is used to restore the degraded image line by line, and the evaluation parameters are used to evaluate the image quality before and after restoration. The evaluation results show that the restoration effect is obvious. It is proved that the two methods proposed in this paper are correct.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TP391.41

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