Calibration method for telecentric camera

Abstract

The invention belongs to the technical field of optical measurement, and discloses a calibration method for a telecentric camera. The method comprises the following steps of (1) establishing a world coordinate system, a camera coordinate system, an image coordinate system and a pixel coordinate system in the projection system of a telecentric camera; (2) extracting feature points in a calibration plate image shot by the telecentric camera and figuring out internal parameters; (3) acquiring the difference between the actual coordinate of a calibration point in the image coordinate system and the coordinate of the calibration point of the world coordinate system projected in the image coordinate system during the distortion of the telecentric camera, figuring out the minimum value of the difference through the Levenberg-Marquardt algorithm, and obtaining the distortion coefficient of the telecentric camera at the minimum value. Based on the calibration method for the telecentric camera, the internal parameters and the external parameters of the telecentric camera are accurately obtained. Therefore, the calibration accuracy of the telecentric camera is improved.

Description

technical field [0001] The invention belongs to the technical field of optical measurement, and more specifically relates to a calibration method for a telecentric camera. Background technique [0002] As a kind of optical measurement, CCD (Charge Coupled Device) imaging technology is the key research direction of computer vision, and camera calibration is an essential step in CCD imaging technology. The process of camera calibration is the process of estimating the internal and external parameters of the camera, that is, estimating the internal parameters of the camera, such as focal length, magnification, distortion coefficient, etc. The external parameters include the rotation matrix and translation vector of the camera relative to the world coordinate system and Relative poses between cameras in a multi-camera stereo vision system. Accurate calibration of camera internal and external parameters can directly improve measurement accuracy. Because the telecentric lens has...

AI Technical Summary

Problems solved by technology

The traditional camera calibration method has high precision, but the calibration speed is slow; the camera self-calibration method only needs to use the corresponding relationship between multiple environmental images during the camera movement process, and does not need a specific calibration reference object; compared to The disadvantage of the traditional camera calibration method is that its algorithm is less robust

The defect of this two-step method is that the principal point coordinates of the camera are simply ignored when constructing the model, and the presence or absence of the principal point coordinates will affect the calibration error of the telecentric camera

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