Study On The Step-by-Step Digital Camera Calibration Method Under 2D Control Of Close-range Photogrammetry

Close-range photogrammetry is a discipline,which by shooting the target image,and then analyze and process the image,to obtain the state of target.Compared with other measurement methods,because of its large amount of information,fast speed and high precision,it is widely used in other areas in addition to mapping.With the development of image processing and computer technology,the ordinary digital camera has gradually become the main source of data acquisition of Close-range photogrammetry,which makes the traditional Close-range photogrammetry have a new development.The ordinary digital camera is different from the professional measurement camera,before used in photogrammetry,it is necessary to make a camera calibration,therefore,the calibration method and image processing method has become one of the hot research topic in Close-range photogrammetry and Computer graphics recently.This paper first analyzes the structural stability of the digital camera,and proves when the common digital camera applicated in photogrammetry is reliability.And then we analyzed the parameter relevance problem,which when use two-dimensional control field to calibrate digital camera’s overall adjustment appeared,at the same time,we make a qualitative analysis,to find the photograph’s angle element how to effect the parameter relevance.In view of strong correlation problem of digital camera calibration under 2D control between interior orientation and exterior orientation elements.This paper proposed a method of step-by-step digital camera calibration under 2D control.This method avoids solving interior orientation and exterior orientation elements at the same time in one adjustment process,and by controlling the photography mode,transforming camera principal distance into the function of distance difference of photography center,and regarding distance difference of photograph center as observation to accurately calculate principal distance.The result of test indicated that the camera distortion parameters solved through this method meet the requirements of close-range photogrammetry,which proved the feasibility of the method.