Thesis (M.S.)--Florida State University, 2002. / Advisor: Dr. Frank B. Gross, Florida State University, FAMU-FSU College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed Oct. 2, 2003). Includes bibliographical references.

This thesis explores underwater imaging solutions in order to alleviate the poor contrast and the distortion in the perception of colour caused by the processes of scattering and absorption. We demonstrate through simulated experiments that imaging systems with higher spectral resolution than RGB could be useful for underwater imaging tasks such as estimating illumination and spectral reflectance values. We also tested hyperspectral imagers in real world experiments and found that the current technology is limited for underwater image enhancement applications. To address the problem of poor visibility in underwater scenes we introduce dehazing methods for underwater RGB images and videos. Current underwater dehazing methods suffer from limitations such as estimated parameters being biased towards pixels of bright objects in a scene and artefacts being created in regions that contain pure haze. Bright objects in a scene are avoided by using texture features during the estimation of parameters and local bias is avoided by taking information from an image at different spatial resolutions. We inhibit noise and artefacts being created in the pure haze regions by segmenting these areas and treating them as a special case. We address the spectral distortion present in underwater scenes by applying a water-type dependent white balancing step. We also demonstrate the application of our method to underwater videos with a weighted temporal smoothing of the estimated parameters and a Gaussian normalisation step that ensures segmentation of pure haze regions is stable across frames. We evaluate our methods both on quantitative metrics and through subjective experiments and demonstrate an improved performance in comparison to the state of the art in underwater image and video enhancement. We also show how no-reference underwater image quality assessment metrics do not always correspond with human judgement and provide suggestions on how they could be improved.

Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 2005. / Includes bibliographical references (p. 173-187).

The maximum number (Nmax) of fish was recorded using baited underwater camera (BUC) techniques to study spatio-temporal changes of the fish community in localize areas. In the central North Sea (~100m depth) abundance models revealed that for both, whiting and flatfish, the Nmax was influenced by light level at the time of deployment. Nmax of hagfish was strongly related to current speed in a non-linear way with a predicted upper threshold (~11 cm.s-1) above which Nmax declined. Current speed and inter-annual variation had an important effect on haddock Nmax. Large predators that prompt avoidance mechanisms (e.g. large conger eel, marine mammals and fishing vessels) and bottom current speed >25 cm.s-1 can modify demersal fish behaviour depending on size and species and therefore have important effects on BUC-derived data. The BUC was applied for the first time to the monitoring of the Buzzard platform, a new oil and gas development in the central North Sea that host 12 demersal and benthic fish species. The benthic taxa, flatfish and hagfish, showed higher numbers closer to the platform whilst the most mobile species showed constant numbers (haddock) or highest numbers outside of the 500m of Exclusion Area (whiting). No significant changes in fish diversity were found between the areas surveyed before the platform construction. After the construction, the species richness and diversity were higher outside the 500m Exclusion Area surrounding the platform. Offshore sand banks, like oil platforms, can modify the composition of the local fish abundance. BUC and commercial trawl observations on the Jones Bank (75-150m depth, Celtic Sea) recorded 23 species, the highest richness, on top of the bank and 18 species on the slope and off-bank areas. Conger eel and Nephrops were both absent from the top of the bank site whereas haddock was only observed in the bank area.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / Title from Web page (viewed on Jan. 5, 2009). Includes bibliographical references (p. 160-174).

No description available.

Thesis (Ph. D.)--University of Rhode Island, 2006. / Typescript. Includes bibliographical references (leaves 97-99).

Thesis (Ph.D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences and the Woods Hole Oceanographic Institution), 2000. / Vita. / Includes bibliographical references (leaves 179-187). / A spectral camera (ALISS - Ambient Light Imaging and Spectral System) was used to image ambient light from high-temperature vents at 9°N East Pacific Rise and the Juan de Fuca Ridge during 1997 and 1998 Alvin dive cruises. ALISS is a low-light digital camera with custom-designed optics. A set of nine lenses, each covered by an individual bandpass filter (50 and 100 nm nominal bandwidths), allows vents to be imaged in nine wavelength bands simultaneously spanning the range of 400-1000 nm. Thus, both spatial and spectral information are obtained. ALISS was used to image three types of vents: black smokers, flange pools, and beehives. The primary source of light is thermal radiation due to the high temperature of the hydrothermal fluid (~350°C). This light is dominant at wavelengths greater than 700 nm. At flange pools, where the fluid is relatively stable, only thermal radiation is present. Black smokers and beehives, however, are subject to mixing with ambient seawater (2°C) leading to mineral precipitation. Data from these types of vents show the existence of non-thermal, temporally varying light in the 400-700 nm region. This light is probably caused by mechanisms related to mixing and precipitation, such as chemiluminescence, crystalloluminescence and triboluminescence. / by Sheri N. White. / Ph.D.

Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), September 2011. / "September 2011." "©2011"--P. 2. Cataloged from PDF version of thesis. / Includes bibliographical references (p. 97-101). / The ocean depths provide an ever changing and complex imaging environment. As scientists and researches strive to document and study more remote and optically challenging areas, specifically scatter-limited environments. There is a requirement for new illumination systems that improve both image quality and increase imaging distance. One of the most constraining optical properties to underwater image quality are scattering caused by ocean chemistry and entrained organic material. By reducing the size of the scatter interaction volume, one can immediately improve both the focus (forward scatter limited) and contrast (backscatter limited) of underwater images. This thesis describes a relatively simple, cost-effective and field-deployable low-power dynamic lighting system that minimizes the scatter interaction volume with both subjective and quantifiable improvements in imaging performance. / by Geoffrey Allen Gorman. / S.M.

Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 2004. / Includes bibliographical references (p. 177-190). / Our ability to image extended underwater scenes is severely limited by attenuation and backscatter. Generating a composite view from multiple overlapping images is usually the most practical and flexible way around this limitation. In this thesis we look at the general constraints associated with imaging from underwater vehicles for scientific applications - low overlap, non-uniform lighting and unstructured motion - and present a methodology for dealing with these constraints toward a solution of the problem of large area 3D reconstruction. Our approach assumes navigation data is available to constrain the structure from motion problem. We take a hierarchical approach where the temporal image sequence is broken into subsequences that are processed into 3D reconstructions independently. These submaps are then registered to infer their overall layout in a global frame. From this point a bundle adjustment refines camera and structure estimates. We demonstrate the utility of our techniques using real data obtained during a SeaBED AUV coral reef survey. Test tank results with ground truth are also presented to validate the methodology. / by Oscar Pizarro. / Ph.D.