Research On The Key Tecnologies Of Compact Three Line Array Aerial Camera

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.