Camera Calibration Robust to Defocus Using Phase-Shifting Patterns

Camera parameters can't be estimated accurately using traditional calibration methods if the camera is substantially defocused. To tackle this problem, an improved approach based on three phase-shifting circular grating (PCG) arrays is proposed in this paper. Rather than encoding the feature po...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2017-10, Vol.17 (10), p.2361
Main Authors: Cai, Bolin, Wang, Yuwei, Wang, Keyi, Ma, Mengchao, Chen, Xiangcheng
Format: Article
Language:English
Subjects:
Calibration
camera calibration
Cameras
Classification
concentric circle
defocus
feature points
Image detection
Parameter estimation
Phase distribution
phase-shifting
Sorting algorithms
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Summary:Camera parameters can't be estimated accurately using traditional calibration methods if the camera is substantially defocused. To tackle this problem, an improved approach based on three phase-shifting circular grating (PCG) arrays is proposed in this paper. Rather than encoding the feature points into the intensity, the proposed method encodes the feature points into the phase distribution, which can be recovered precisely using phase-shifting methods. The PCG centers are extracted as feature points, which can be located accurately even if the images are severely blurred. Unlike the previous method which just uses a single circle, the proposed method uses a concentric circle to estimate the PCG center, such that the center can be located precisely. This paper also presents a sorting algorithm for the detected feature points automatically. Experiments with both synthetic and real images were carried out to validate the performance of the method. And the results show that the superiority of PCG arrays compared with the concentric circle array even under severe defocus.
ISSN:1424-8220
1424-8220
DOI:10.3390/s17102361