Calibrating method based on fixed parameters and variable parameters for three-dimensional scanning system

Abstract

A calibration method based on fixed and variable parameters in three-dimensional scanning system relates to the camera model parameter calibration in the visual system including the following steps: (1) fixed parameters calibration is primarily to acquire coordinates of sampling points on circular contour and heart in image coordinates through image processing techniques, and then use n sampling points to get aspect ratio through least squares method, (2) after obtaining the fixed parameters, it uses the image coordinates of image midpoint and the corresponding space coordinates of world midpoint to demarcate the initial value of variable parameters for the camera, including the equivalent focal length, main point coordinates, axis tilt factor, distortion factor and external parameters, (3) after demarcation, it takes fixed parameters as a constraint for nonlinear optimization objective function to establish a binding target function and get the optimal solution of variable parameters through the nonlinear optimization method.

Description

technical field [0001] The invention relates to the calibration of camera model parameters in a vision system, in particular to a calibration method based on fixed parameters and variable parameters in a three-dimensional scanning system. Background technique [0002] One of the basic tasks of computer vision is to calculate the three-dimensional information of the object in the field of view from the image captured by the camera, so as to reconstruct and recognize the three-dimensional object. The relationship between the three-dimensional geometric information of the object surface point and its corresponding point on the image is determined by the imaging model of the camera. The process of establishing this geometric model is actually the solution process of the camera parameters. Therefore, the calibration of camera parameters is the premise and key of this modeling process. The process of solving the camera parameters is called camera calibration. [0003] The docume...

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Problems solved by technology

This is because in each measurement, if the internal parameters are considered to be constant and not calibrated, but in fact some variable parameters in the internal parameters will change, which will affect the system accuracy; if the internal parameters are calibrated every time, but limited to Due to the conditions of the measurement site, the calibration error of some fixed values ​​in the internal parameters will be relatively large, resulting in an increase in the system error

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