光学学报, 2017, 37 (2): 0211001, 网络出版: 2017-02-13   

航空相机像旋动态调制传递函数分析与研究

Dynamic Modulation Transfer Function Analysis and Research of Image Rotation for Aerial Camera
作者单位
1 中国科学院长春光学精密机械与物理研究所航空成像与测量重点实验室, 吉林 长春 130033
2 中国科学院大学, 北京 100049
3 中国科学院长春光学精密机械与物理研究所航空成像与测量创新实验室, 吉林 长春130033
摘要
航空相机在采用旋转扫描反射镜成像过程中存在像面旋转,会导致图像模糊,成像质量下降,必须采用像旋补偿机构进行补偿。目前,通过人眼观察图像模糊程度和电机同步控制精度评价像旋补偿精度,都不能客观准确评价系统成像质量。为建立航空相机成像质量与像旋补偿系统其他指标之间的直接关系,提出基于极坐标系的动态调制传递函数(MTF),并提出基于倾斜刃边法与模糊路径法相结合的方法测量航空相机旋转像移动态MTF。设计扇形靶标旋转动态成像实验,利用旋转动态MTF和倾斜刃边法得到图像动态MTF计算值,并基于图像模糊路径测量转台转动时图像动态MTF测量值。实验结果表明,转台以20~300(°)/s匀速转动时,空间频率在旋转动态MTF到达第一个零点频率前,动态MTF计算值和测量值曲线近似重合,验证了旋转动态MTF的正确性;空间频率在小于0.7零点频率范围内,两动态MTF曲线相对误差最大值和均值分别小于6%,2%,进而证明了测量方法的准确性。
Abstract
Aerial camera causes image rotation problem in the process of rotating scanning reflector imaging, which leads to image blur and degradation of image quality, so image rotation compensation system is essential for aerial camera. At present, the distinguishing image blur by human eyes and synchronization control accuracy by electrical machine are used to evaluate compensation performance of image rotation, but the image quality could not be evaluated objectively and accurately. In order to establish the direct relationship between imaging quality of aerial camera and other index of rotating compensation system, the dynamic modulation transfer function (MTF) based on polar coordinate is proposed. A new method combined with the slanted-edge method and blur path method is proposed to measure the dynamic MTF of rotation image motion of the aerial camera. The rotating dynamic imaging experiments are designed with sector target, and the image dynamic MTF calculated values are obtained using the rotating dynamic MTF and slanted-edge method. The image dynamic measured MTF values are obtained based on image fuzzy path. Experimental results show that, when rotate table with variable angular velocities from 20 (°)/s to 300 (°)/s, the spatial frequency is less than first zero frequency of rotating dynamic MTF, and the two dynamic MTF curves are approximately coincide. Thus the correctness of the rotating dynamic MTF is demonstrated. When the spatial frequency is less than 0.7 of zero frequency, the maximum values and mean values of dynamic MTF relative errors are less than 6%, 2% respectively, thus the accuracy of the measurement method is proved.

刘超, 丁亚林, 田大鹏, 杜言鲁, 孙崇尚. 航空相机像旋动态调制传递函数分析与研究[J]. 光学学报, 2017, 37(2): 0211001. Liu Chao, Din Yalin, Tian Dapeng, Du Yanlu, Sun Chongshang. Dynamic Modulation Transfer Function Analysis and Research of Image Rotation for Aerial Camera[J]. Acta Optica Sinica, 2017, 37(2): 0211001.

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