Optics and Precision Engineering, Volume. 30, Issue 4, 478(2022)
Two-step calibration for vision measurement system with large field of view and high depth
To address the problems of low calibration accuracy, difficulties in large target fabrication, and complicated operation in engineering fields, a two-step camera calibration method for vision measurement system with a large field of view is herein proposed and implemented based on industrial close range photogrammetry. The mathematical model of the perspective model of camera imaging is investigated. First, in the close range, the calibration of the internal parameters at the front section is realized using a small-scale cross target and the pyramid method. Second, in the far range, several coding mark points are arranged in the measured space, and the external parameters are calculated based on the principle of single image intersection. Finally, all the internal and external parameters are optimized using bundle adjustment. To verify the feasibility and accuracy of the proposed method, a vision experiment with a large field of view is carried out. Experimental results show that the re-projection error is less than 0.08 pixels, the maximum absolute error of the three-dimensional measurement is 0.43 mm, and the pitch angle error of the rotor with a diameter of 10 m is less than 0.1°. It is therefore proved that the method can be used to achieve internal as well as external parameter calibration in the external field separately.
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Hao HU, Bin WEI, Jin LIANG, Huigang WANG, Yongqing ZHANG. Two-step calibration for vision measurement system with large field of view and high depth[J]. Optics and Precision Engineering, 2022, 30(4): 478
Category: Information Sciences
Received: Jul. 22, 2021
Accepted: --
Published Online: Mar. 4, 2022
The Author Email: WEI Bin (weibin0@126.com)