全景式航空相机摄影起始角误差抑制方法

Restraining method of imaging starting angle error for panoramic aerial camera

覆盖宽度是全景式航空相机的重要指标,深入分析了摄影起始角误差对全景式航空相机所得图像锯齿效应的影响。在介绍全景式航空相机工作方式及工作时序的基础上,分析了所得图像边缘差异占覆盖宽度的比值γ与目标倾斜角、横向扫描角及摄影起始角误差之间的关系。全景式航空相机工作时,通常对摄影起始角设定预留恒定角度值,该方法会造成较大的摄影起始角误差。为了减小该误差,提出了改进迭代算法:在每帧成像时记录摄影起始角误差,并利用该误差对下一帧图像进行修正。最后给出了实验结果。结果表明:采用传统算法和改进迭代算法时,摄影起始角误差均方根值分别为0.045°和0.005°,γ值范围分别为[0.009 1,0.014 8]、[0.001 0,0.001 7]。改进迭代算法将摄影起始角误差降低为传统算法的1/9,对应γ最大值为0.001 7,满足工程需求。

Covering width is an important index of the panoramic aerial camera, so the effect of imaging starting angle error on the sawtooth result of panoramic aerial camera imaging was analyzed in detail. Based on introducing the operating mode and scheduling of panoramic aerial camera, the relationship between the ratio, which was defined as γ of image margin difference to covering width, target slope angle, transverse scanning angle and imaging starting angle error was given. When panoramic aerial camera was on operating, one special constant angle was reserved for the imaging starting angle. The imaging starting angle error would be appreciably high when this method was used. So improved iterative arithmetic was imported. In the improved method, the imaging starting angle error of every frame was recorded and was used to correct that of next frame. At last, experimental result was given. Result shows that the root-mean-square of imaging starting angle errors are respectively 0.045° and 0.005° when general and improved methods are used. And the corresponding ranges of γ are [0.009 1,0.014 8] and [0.001 0,0.001 7]. Compared with general method, the imaging starting angle error is reduced to be 1/9 when induced iterative arithmetic is used, and the corresponding maximum of 7 is 0.001 7, which could comply with engineering requirement.