A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Holistic calibration algorithms of stereo deflectometry are generally based on iterative computation and therefore heavily sensitive to the accuracy of input initial values. Image distortion seriously affects the estimation accuracy of the initial value, which causes the iterative computation to converge in the wrong position or unable to converge. An algorithm is presented to increase the accuracy and robustness of the calibration of a stereo deflectometry system. Firstly, based on the knowledge that distortion of the pixels which close to image center can be ignored, a search window with a certain border length is placed at image center. The border size of the window can be determined according to the proposed algorithm and experimental results. Secondly, considering distortion center and image center cannot normally coincide in an actual imaging system, the search window is moved within the image sequentially. Accurate initial values are searched with the window moving, and determined by making the proposed evaluation function reach the minimum. Experimental results affirm the proposed algorithm can significantly improve the calibration accuracy of a stereo deflectometry system. The RMS (root mean square) of calibration error can be reduced to 0.05 pixels from 0.31 pixels by using the proposed algorithm.
LanguageEnglish
Title of host publicationInternational Conference on Optical and Photonic Engineering
Subtitle of host publicationicOpen Proceedings
PublisherSPIE
Publication statusAccepted/In press - 16 Jul 2019
EventInternational Conference on Optical and Photonic Engineering - Phuket, Thailand
Duration: 16 Jul 201920 Jul 2019
http://www.icopen.net/

Publication series

NameProceedings of SPIE
PublisherSPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceInternational Conference on Optical and Photonic Engineering
Abbreviated titleicOPEN 2019
CountryThailand
Period16/07/1920/07/19
Internet address

Fingerprint

Calibration
Pixels
Function evaluation
Imaging systems

Cite this

Xu, Y., Gao, F., & Jiang, X. (Accepted/In press). A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry. In International Conference on Optical and Photonic Engineering: icOpen Proceedings (Proceedings of SPIE). SPIE.
Xu, Yongjia ; Gao, Feng ; Jiang, Xiangqian. / A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry. International Conference on Optical and Photonic Engineering: icOpen Proceedings. SPIE, 2019. (Proceedings of SPIE).
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title = "A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry",
abstract = "Holistic calibration algorithms of stereo deflectometry are generally based on iterative computation and therefore heavily sensitive to the accuracy of input initial values. Image distortion seriously affects the estimation accuracy of the initial value, which causes the iterative computation to converge in the wrong position or unable to converge. An algorithm is presented to increase the accuracy and robustness of the calibration of a stereo deflectometry system. Firstly, based on the knowledge that distortion of the pixels which close to image center can be ignored, a search window with a certain border length is placed at image center. The border size of the window can be determined according to the proposed algorithm and experimental results. Secondly, considering distortion center and image center cannot normally coincide in an actual imaging system, the search window is moved within the image sequentially. Accurate initial values are searched with the window moving, and determined by making the proposed evaluation function reach the minimum. Experimental results affirm the proposed algorithm can significantly improve the calibration accuracy of a stereo deflectometry system. The RMS (root mean square) of calibration error can be reduced to 0.05 pixels from 0.31 pixels by using the proposed algorithm.",
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author = "Yongjia Xu and Feng Gao and Xiangqian Jiang",
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series = "Proceedings of SPIE",
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Xu, Y, Gao, F & Jiang, X 2019, A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry. in International Conference on Optical and Photonic Engineering: icOpen Proceedings. Proceedings of SPIE, SPIE, International Conference on Optical and Photonic Engineering, Thailand, 16/07/19.

A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry. / Xu, Yongjia; Gao, Feng; Jiang, Xiangqian.

International Conference on Optical and Photonic Engineering: icOpen Proceedings. SPIE, 2019. (Proceedings of SPIE).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

TY - GEN

T1 - A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry

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AU - Gao, Feng

AU - Jiang, Xiangqian

PY - 2019/7/16

Y1 - 2019/7/16

N2 - Holistic calibration algorithms of stereo deflectometry are generally based on iterative computation and therefore heavily sensitive to the accuracy of input initial values. Image distortion seriously affects the estimation accuracy of the initial value, which causes the iterative computation to converge in the wrong position or unable to converge. An algorithm is presented to increase the accuracy and robustness of the calibration of a stereo deflectometry system. Firstly, based on the knowledge that distortion of the pixels which close to image center can be ignored, a search window with a certain border length is placed at image center. The border size of the window can be determined according to the proposed algorithm and experimental results. Secondly, considering distortion center and image center cannot normally coincide in an actual imaging system, the search window is moved within the image sequentially. Accurate initial values are searched with the window moving, and determined by making the proposed evaluation function reach the minimum. Experimental results affirm the proposed algorithm can significantly improve the calibration accuracy of a stereo deflectometry system. The RMS (root mean square) of calibration error can be reduced to 0.05 pixels from 0.31 pixels by using the proposed algorithm.

AB - Holistic calibration algorithms of stereo deflectometry are generally based on iterative computation and therefore heavily sensitive to the accuracy of input initial values. Image distortion seriously affects the estimation accuracy of the initial value, which causes the iterative computation to converge in the wrong position or unable to converge. An algorithm is presented to increase the accuracy and robustness of the calibration of a stereo deflectometry system. Firstly, based on the knowledge that distortion of the pixels which close to image center can be ignored, a search window with a certain border length is placed at image center. The border size of the window can be determined according to the proposed algorithm and experimental results. Secondly, considering distortion center and image center cannot normally coincide in an actual imaging system, the search window is moved within the image sequentially. Accurate initial values are searched with the window moving, and determined by making the proposed evaluation function reach the minimum. Experimental results affirm the proposed algorithm can significantly improve the calibration accuracy of a stereo deflectometry system. The RMS (root mean square) of calibration error can be reduced to 0.05 pixels from 0.31 pixels by using the proposed algorithm.

KW - deflectometry

KW - calibration

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M3 - Conference contribution

T3 - Proceedings of SPIE

BT - International Conference on Optical and Photonic Engineering

PB - SPIE

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Xu Y, Gao F, Jiang X. A search algorithm for accuracy improvement of holistic calibration of stereo stereo deflectometry. In International Conference on Optical and Photonic Engineering: icOpen Proceedings. SPIE. 2019. (Proceedings of SPIE).