This dissertation presents a novel underwater machine vision technique which uses
the optical properties of water to extract range information from colour images. By
exploiting the fact that the attenuation of light in water is a function of frequency, an
intensity-range transformation is developed and implemented to provide monocular
vision systems with a three-dimensional scene reconstruction capability. The technique
can also be used with images that have no salient, contrasting features and there are no
restrictions on surface shapes.
From a generalized reflectance map based on the optical properties of water, the
closed form intensity-range transformation is derived to convert intensity images from
various spectral bands into a range map wherein the value of each "pixel" is the range to
the imaged surface. The technique is computationally efficient enough to be performed
in real time and does not require specialized illumination or similar restrictive conditions.
A calibration procedure is developed which enables the transformation to be practically
implemented. An alternate approach to estimating range from multispectral data based on
expanding the medium's transfer function and using these terms as elements in sensitivity
vectors is also presented and analyzed.
Mathematical analysis of the intensity-range transformation and associated
developments is provided in terms of its performance in noise and sensitivity to various
system parameters. Its performance as a function of light scattering is studied with the
aid of computer simulation. Results from transforming actual underwater images are also
presented. The results of this analysis and the demonstrated performance of the
intensity-range transformation endorse it as a practical enhancement to underwater
machine vision systems. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/8194 |
| Date | 25 May 2017 |
| Creators | Randell, Charles James |
| Contributors | Collins, James S., Lu, Wu-Sheng |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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