航空相机的像旋转特性分析及其补偿方法

Characteristic analysis and correction technique about the image rotation of aerial camera

航空相机在多航迹成像方式中,随着45°反射镜绕光轴旋转对物进行扫描,物体反射像也将绕光轴进行旋转,为此必须采取消除像旋转的措施来保证成像质量。为阐述产生像旋转的原因,分析了扫描反射镜的像旋转特性;并在探讨消除像旋技术理论的基础上,提出了一种反射镜与探测器同步转动消除像旋转的方法。在多航迹工作方式中,此方法为相机扫描机构连续扫描成像提供了必要条件。利用此方法还改进了以往步进式扫描机构的惯量大、扫描效率低的问题,并在实际工程中得以应用和证明。试验结果表明,该方法的同步旋转误差小于1/3像元,能够获得良好的图像效果。

While aerial camera took pictures by way of many airlines and its 45° scanning mirror rotates and scans terrestrial object, the reflected image of the object rotates around the optical axis. It is necessary to eliminate the image rotation so as to maintain its image quality. Based on the cause of the image rotation, the image rotation characteristic of the scanning mirror was analyzed. And through the exploration of the techniques for eliminating the image rotation, one method in which the mirror and its detector rotate synchronously was suggested. The scanning device could image in continuous scanning way and need not remain stationary as step scanning imaging devices. Moreover, this method could solve the problem of large inertia and low scanning efficiency of conventional step scanning devices. It had been applied and evidenced in practical engineering. Test results show that the rotation synchronous error is less than one-third of pixel size and that good images can be acquired without any blurring.