A large field of view camera calibration method based on laser tracker

Abstract

The invention belongs to the field of visual measurement, and relates to a large-view-field camera calibration method based on a laser tracker. According to the method, a calibration board is manufactured according to the characteristics of the laser tracker; the images of the calibration board of different positions and angles are photographed by a camera, and the distribution position of the calibration board covers the field of view of the camera; angular point detection is performed on the calibration board by utilizing angular point detection tool software, and the angular position detection results of the central area of the calibration board are selected; the world coordinate system coordinates of the angular points of the central area of the calibration board are calculated by utilizing the target spherical coordinates of the four corners of the calibration board; and the internal matrix and the external matrix of the camera are calculated by utilizing a direct linear transformation method, and the radial distortion coefficient is iteratively calculated so that a high-precision calibration result is obtained. The problem of the linear transformation method that the large high-precision calibration board requires to be manufactured for the requirement of large-view-field calibration can be solved, and the measurement characteristics of the laser tracker are favorable for arrangement of the calibration board at an appropriate angle so that the operability and the calibration precision can be enhanced. The method is suitable for calibration of the large-view-field camera.

Description

technical field [0001] The invention belongs to the field of visual measurement, in particular to a method for calibrating a camera with a large field of view based on a laser tracker. Background technique [0002] The calibration of the camera is the key to the measurement of the camera-based vision system. The internal and external parameters and distortion coefficients of the camera obtained through calibration have a great influence on the measurement accuracy of the vision system. In the calibration of large field of view, the field of view of the camera is larger and farther away. Large and high-precision targets are difficult to process, transport and maintain, and it is also difficult to apply in actual scenes. Small targets can only cover a small part of the field of view. The camera calibration results bring huge errors, and the calibration accuracy is unevenly distributed in the field of view. [0003] In the existing technical literature, the invention patent "C...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the pre-calibration control points need to be collected one by one, high-precision measurement requires a large number of control points, and the acquisition of pre-calibration control points takes a long time

In addition, in this method, the 3D world coordinate system of the on-site control points is directly calculated with the pre-calibrated parameters, but the internal and external parameters have changed due to reasons such as temperature after the camera is replaced, and the calculated results will have errors. The calibration link will not be able to resolve this part of the error

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