【作者】 王超；

【导师】 陈娟；

【作者基本信息】 中国科学院长春光学精密机械与物理研究所 ， 机械电子工程， 2017， 博士

【摘要】 三线阵航摄仪通过三个视角的线阵推扫成像,可以有效提高立体测绘精度,降低摄影测量过程对地面控制点的依赖,并且提供了多光谱成像的扩展能力,在数据生产效率和影像质量方面有明显的优势。几款主流的三线阵航摄仪存在体积大、重量大、操作复杂、时效性差等缺点,相比之下,轻型机和无人机遥感系统具有续航时间长、成本低、机动灵活、操作简便等优点。因此本课题将重点研究轻小型三线阵航摄仪系统的关键技术,突破三线阵航摄仪轻小型化工程应用的关键难题,实现系统在测绘遥感领域中的规模化应用。本课题所研究的关键技术主要围绕航摄仪的光学成像技术和制图测量技术展开,主要研究的内容包括以下几点:1.提出了轻小型三线阵航摄仪系统的成像模式和总体方案,给出了航摄仪的指标体系和结构布局,提出了基于单镜头搭配新型COMS光电探测器的成像系统方案。完成了像方远心光学系统和双高斯光学系统的设计与优化,并对光谱特性、调制传函、系统畸变、像差、相对照度均匀性、公差分配、体积重量和加工装调难度等进行了详细的对比与分析。由于光谱特性、畸变参数、成像能力和环境适应性的优势,选用了像方远心光学系统的镜头结构形式。该光学系统的视场达到80°,在80lp/mm的空间频率处,光学系统调制传递函数优化至0.4,系统畸变最大值优化至0.1%,并且光学元件重量控制在1.3kg以内。经过光学系统的环境适应性分析,选择了温度适用范围更优的钛合金材料,对环境温度、大气压强和航摄高度进行了仿真计算,并且对机载力学环境下的光机结构稳定性进行了仿真计算,各项指标均能满足系统总体要求。2.基于航空测绘遥感领域的应用需求,该航摄仪系统的制图精度需要达到1:500、1:1000和1:2000比例尺标准的精度等级。根据摄影测量理论的前方交会原理,分析推导了轻小型三线阵航摄仪直接定向模式下的地物定位误差模型,并完成了系统各误差项的敏感度分析,得到位置测量精度、姿态测量精度、相机标定精度等主要误差项。并结合系统体积重量的约束,对关键组件进行了选型。对三线阵航摄仪的数据时钟同步系统进行了设计与分析,提出了校时、守时和用时的数据同步流程,同步精度达到微秒量级,实现了航摄仪系统外方位元素和线阵影像的高精度配准。最后,将多余度影像匹配和空中三角测量环节融入制图精度分析模型中,得到该系统的航测成果平面定位精度能够达到0.3m,数字高程模型精度可达到0.25m。3.提出了基于衍射光学元件的相机几何参数标定系统方案,该方法具有精度高、成本低、分析速度快等特点。对系统中的激光器、准直透镜、空间滤波器和滤光片等关键组件进行了分析与选型,利用模拟退火算法,对衍射光栅的掩模板图案和坐标参数进行了优化设计。在标定系统中,对基于径向畸变约束的相机标定算法进行了改进,设计并开发了相机标定数据处理流程和软件,最终将量测相机内方位元素的标定精度提高至微米量级,完成与室外三维标定场测试结果的对比分析。另外,介绍了三线阵航摄仪系统视准轴误差的检校原理,给出系统姿态测量的坐标变换关系,提出综合数据时钟同步的视准轴误差的解算模型。利用航摄任务中的地面检校场,通过空中三角测量法,对系统视准轴误差进行了解算与修正。利用相机标定检校数据,完成了典型地貌的测图精度试验,其测图精度结果满足国家标准规定的大比例尺制图精度要求。更多还原

【Abstract】 A line scan camera is one of two principal digital cameras used in aerial photogrammetry,and the other is a frame camera.Compared to a frame camera,a line scan camera usually has higher resolution but low cost,its optics is also simple and compact,and image size is flexible in the along-track direction.A three-line-array push-broom camera,which has three linear CCDs being placed in the optical focal plane,can provide 3D information of an object through its stereoscopic views.Several mainstream three line array aerial camera has large volume and weight,complex operation and poor timeliness.In contrast,prop plane and unmanned aerial vehicle remote sensing system has the advantages of long life,low cost,flexible and convenient operation etc..This thesis will focus on the key technology of compact three line array aerial camera system.Realize the application of large scale in the field of surveying and remote sensing.The key technology of this thesis is mainly focused on the optical imaging technology and the surveying and mapping technology:1.Imaging mode and overall scheme of compact three line array aerial camera system are proposed.The design and optimization of image telecentric optical system and double Gauss optical system have brought.And the characteristics of the spectrum,modulation transfer function,system distortion and aberration,relative illumination uniformity,tolerance allocation,volume weight and fabrication complexity are compared and analyzed in detail.Because of the advantages of spectral characteristics,distortion parameters,imaging ability and environmental adaptability,the structural form of telecentric optical system is selected.The imaging field of the optical system reached 80 degrees.The modulation transfer function of the optical system is optimized to 0.4 at the spatial frequency of 80lp/mm.And the maximum distortion is optimized to 0.1%,and the weight of the optical element is controlled within 1.3kg.2.Based on the application requirements of aerial surveying and mapping remote sensing field,the precision of the aerial photographic system needs to achieve the precision of 1:500,1:1000 and 1:2000 scale.According to the principle of intersection photogrammetry theory,the object positioning error model of compact three linear aerial camera system by direct oriented mode is deduced.The sensitivities of the errors in the system are analyzed,and the main error items such as position measurement accuracy,attitude measurement accuracy and camera calibration accuracy are obtained.The geometric position and stability of the optical system can be fixed by appropriate methods of construction such that the images are reproducible.The plane precision of the aerial mapping system can reach 0.2~0.3m,and the elevation accuracy can reach 0.15~0.25 m.3.The purpose of geometric camera calibration is to establish an unequivocal relationship between points on an image plane and the object space.Traditional methods for geometrical camera calibration are based on calibration grids or single pixel illumination by collimated light.A new method for geometrical sensor calibration by means of Diffractive Optical Elements(DOE)in connection with a laser beam equipment is presented.This method can be especially used for 2D-sensor array systems but in principle also for three line scanners.And the theory and method of the boresight misalignment calibration of integrated GPS/IMU are introduced.A corresponding function model is established.Based on the test flight data,not only validates the validity and the feasibility of the boresight misalignment model,but also analyses the accuracy of aerial triangulation by using the model mentioned above.更多还原