Study On Camera Calibration For Astronomical Photogrammetry

Geodetic astronomical measurements mainly measure the astronomical warp,latitude and astronomical azimuth of the ground control points by observing the stars.With the development of the photographic theodolite,it is urgent to use the method of photogrammetry to automatically measure the celestial orientation.In the data processing of astronomical photogrammetry,the internal and external parameters and distortion parameters of the camera need to be calibrated.In this paper,the principle and algorithm of photogrammetry and the theory of geodetic astronomy are used to find a basic technique and method to realize astronomical photogrammetry.By photographing common stars,the observational model of astronomical photogrammetry is established to calculate the camera parameters for astronomical measurement.The main contents of this article include:(1)This paper introduces the imaging model of photogrammetry and the possible distortion type of camera lens,and establishes the function relation between the coordinates of Image point and control point by Collinear equation,and deduces the camera calibration model according to the image distortion.(2)from the time system and the celestial coordinate system,the Earth in the space of irregular movement caused by the problem to make corrections,such as precession,nutation and so on.Then,the influence of atmospheric refraction on astronomical observation is analyzed,and the calculating method and formula of visual position of stars are introduced indetail.(3)The images of the sun,Moon and stars were photographed in the experiment,and the central coordinates of the star map were extracted by using different image processing algorithms for the imaging characteristics of different stars.(4)According to the model of analytic photogrammetry,according to the method of astronomical measurement,by simulating the distribution of the star point in the field of view,the star is photographed,the center coordinates of the star coordinates and the star map are computed,and the internal and external parameters of the camera are solved Realize camera calibration for astronomical photogrammetry.