The Improvement Of The CCD Camera Calibration Method Based On The Plane Bound

CCD camera calibration technique is the vital part of the image measurementsystem, the accuracy of the CCD camera calibration parameters directly determines theaccuracy of the image measurement system. With the improving demand of the precisionof image measurement, the robustness and accuracy of the CCD camera calibrationtechnique are also higher demand.CCD camera calibration, that is, to determine the geometric parameters and opticalparameters of the CCD camera imaging model and the rientation of the camera in theworld coordinate system. For camera calibration, a series of methods have been putforward, the focus of current research is to find a calibration method with goodapplicability and high precision on specific applications. In this paper, the improvedcalibration method is for the two-dimensional image measurement of the parts based onthe existing calibration technique based on plane bound. Through simulation experimentsand real experiments,it shows that the accuracy and robustness of the calibration methodin this paper have been greatly improved. At the same time in order to precisely find thecorner point, this paper researched the sub-pixel corner detecting method based on theHarris and Forstner Operator, and improved the computing speed and positioningaccuracy through enhancing the Forstner Operator.In this paper, the results of CCD camera calibration parameters were used tomeasure the two-dimensional size of the parts in image measurement system,thatwas,based on CCD camera parameters, to obtain the the world coordinates of the edgepoints of the parts through the image information of the parts and to achieve themeasurement of the size of the parts in the world coordinate system. In order to improvethe measuremental accuracy,this paper also studied the sub-pixel edge positioningtechnology,improved the computing speed through enhancing the sub-pixel edgedetecting technology based on Spatial moment,and guaranteed the real-time onlinemeasurements.This article is divided into six chapters shown as follows: I. IntroductionIntroduced the current CCD camera calibration techniques and their respectiveadvantages and disadvantages, on the basis of which this paper put forward a improvedCCD camera calibration method.II. The imaging principle and model of CCD cameraFirstly, introduced the main structure and working principle of the CCD camera;Secondly,introduced the definition of the coordinate systems of the CCD camera imagingmodel, and established the linear model in accordance with imaging principles of pinholecamera; Finally, introduced the main types of the CCD camera lens distortion and theirrespective mathematical expression, and according to the actual situation, onlyconsidering the radial distortion of camera lens, established the non-linear imaging modelof the CCD camera.III. the improved CCD camera calibration method based on plane boundThis article discribed the methods of calibrating the camera parameters in detail; Forthe Corner extraction of the image, improved the existing sub-pixel corner extractiontechnology ,and enhanced the speed and positioning accuracy.IV. The robustness and accuracy analysis of the calibration method in this paperThrough simulation experiments and real experiments, analyzed the impact of thenoise and the number of calibration board image on calibration results；And verified thatthe accuracy and robustness of calibration method of this paper have been improvedmarkedly by comparing with Zhang's method.V. The application of the calibration results in the measurement of partsFirstly,introduced the principle of using the calibration methods of this paper tomeasure the size of parts, and enhanced the computing speed by improving the existingsub-pixel edge detecting methods based on Spatial moment; Secondly, analysed theaccuracy of image measurement using camera parameters through simulationexperiments,and further improved the measurement accuracy by improving theexpression of radial distortion of CCD camera;Finally, analysed the measurementalaccuracy when this paper's calibration method was used in the image measurement, aswell as the impact of the accuracy of camera calibration on the accuracy of measuringthrough Experimental measurement of the standard gauge block.VI. ConclusionSummarized the research,analysed the shortcomings of this article,and pointed out the entry point of the in-depth study for the next step.