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Permanent link (DOI): https://doi.org/10.7939/R3ZC7S30V

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Underwater Camera Calibration and 3D Reconstruction Open Access

Descriptions

Other title
Subject/Keyword
Underwater
Calibration
Reconstruction
Dispersion
3D
Refraction
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Yau, Timothy HY
Supervisor and department
Gong, Minglun (Computing Science)
Yang, Herbert (Computing Science)
Examining committee member and department
Yang, Herbert (Computing Science)
Gong, Minglun (Computing Science)
Basu, Anup (Computing Science)
Department
Department of Computing Science
Specialization

Date accepted
2014-05-08T11:22:23Z
Graduation date
2014-11
Degree
Master of Science
Degree level
Master's
Abstract
The recovery of 3D information from 2D images is a well-studied problem in computer vision, with many competing methods that can achieve highly accurate results. However, relatively little attention has been paid to the problem of 3D reconstruction in underwater environments. When cameras are placed underwater they must be protected by a waterproof housing, often featuring a flat glass port through which the scene is viewed. Light rays passing from water into the housing are bent by refraction, a nonlinear process that renders the standard perspective camera model invalid. In spite of this, it is common practice in photogrammetry studies to treat refraction as a radial lens distortion, which can lead to errors in the measured 3D information. Recent research has acknowledged that a physically-correct model of refraction is needed to obtain accurate 3D reconstructions in underwater environments. One important and necessary step is to calibrate the parameters of such a refraction model. In this thesis we develop a novel calibration method that exploits the dispersion of light, which is the angular separation of different wavelengths during refraction, and show that better accuracy is achieved compared to previous work. We then show how to adapt existing reconstruction algorithms to use the physical refraction model, and combine it with our calibration method to obtain a complete process for underwater 3D reconstruction. By analyzing the reconstruction results and comparing against the standard perspective model approximation, we identify the shortcomings of the latter and reveal situations where the refraction model is indispensable. Lastly, we apply the techniques developed in this thesis to real data captured by an underwater observatory and obtain high quality 3D reconstruction results.
Language
English
DOI
doi:10.7939/R3ZC7S30V
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
T. Yau, M. Gong, and Y.H. Yang, "Underwater Camera Calibration using Wavelength Triangulation," Proc. IEEE Conf. on Computer Vision and Pattern Recognition, June 25-27, 2013, Portland, Oregon.

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