An effective method for camera calibration in defocus scene with circular gratings. (March 2019)

• Record Type: Journal Article
• Authors: Cai, Bolin; Wang, Yuwei; Wu, Jiajun; Wang, Mengyu; Li, Fei; Ma, Mengchao; Chen, Xiangcheng; Wang, Keyi
• Is Part Of: Optics and lasers in engineering. Volume 114(2019)
• Page Start: 44
• Page End: 49
• Publication Date: 2019-03
• Subjects: Defocus -- Camera calibration -- Concentric circles -- Phase-shifting; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2018.10.011
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: Our method can calibrate the out-of-focus camera effectively. The pattern contains three gratings simplify the calibration target for defocusing calibration. The entire process requires no metric measurement of the test pattern. The method can be applied in long-range vision systems for it can reduce the size of calibration target. Abstract: Conventional camera calibrations with circular patterns always require sharp target images and thus fail if the images are blurred. In this paper, we present an effective calibration approach using three circular gratings, which can be employed in defocus scene. Rather than using the concentric circles as the targets, the proposed method utilizes circular gratings generated by phase-shifting methods. The intrinsic parameters of the camera can be obtained with the images of circular points, and it works even if the camera is out-of-focus. Numerical simulation and real data experiments have been carried out to validate the method. And the results show that our method can calibrate the camera effectively even under severe defocus. Moreover, the entire process requires no metric measurement of the test pattern, which is very flexible to implement and suitable for people who are not familiar with computer vision.