Approved for public release; distribution is unlimited. / SeaWiFS data converted to optical properties of the ocean in the form of vertical and horizontal underwater visibility products are compared to in-water diver and optical instrument measurements during the Model Diver Visibility (MoDiV) experiment. Results were collected from 19 to 21 August in the Mississippi Bight region of the United States. The SeaWiFS satellite data was processed with the Automated Processing System (APS), developed by the Naval Research Laboratory (Code 7333). APS converted radiance values into specific parameters studied: the beam attenuation coefficient, the diffuse attenuation coefficient, vertical visibility and horizontal visibility. These values were compared to the AC-9instrument, a-Beta instrument, Secchi disk and the observed visibilities from the divers. The results indicated that the beam attenuation coefficient and the diffuse attenuation coefficient are underestimated as compared to the in-situ measurements. These values then overestimate the vertical and horizontal visibility as compared to the Secchi disk and diver sightings. The visibility products from SeaWiFS should be used on an experimental basis for Naval Operational Planning. It is recommended that the use of in-water diver reports noting variability of SeaWiFS visibility product estimates are necessary for validation and offers feedback to the research and development field for algorithm improvement. / Lieutenant, United States Navy

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2003. / Thesis advisor(s): Philip A. Durkee. Includes bibliographical references (p. 57-59). Also available online.

Thèse (Doctorat 3e cycle)--Université de Paris VI. / Includes bibliographical references (leaves 68-75).

Thesis (Ph. D.)--Massachusetts Institute of Technology, 1966. / Bibliography: leaves 86-88.

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

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 80-85). Also available on the Internet.

Thesis (Ph. D.) -- University of Maryland, College Park, 2005. / Thesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Note:

The underwater optical climate of Lake Texoma was measured at eleven fixed stations from August 1996 to August 1997. Secchi transparency and submarine photometry characterized seasonal and spatial values of secchi depth (SD), vertical attenuation coefficient (η''), and depth of euphotic zone (Zeu). Indices of Zeu:SD and η'' × SD were compared with universally applied values derived from inland and coastal waters. Turbidity explained 76% of the variation (p = 0.0001) of η'' among water quality parameters, including chlorophyll-α. Using a spectroradiometer, spectral signatures of chlorophyll-α and turbidity were located. Stations with low turbidity exhibited a distinct green reflectance peak around 590-610 nanometers, indicating presence of chlorophyll-α. Stations with high turbidity exhibited a reflectance peak shift towards the red spectrum, making it difficult to detect the chlorophyll signature. Derivative analysis of the reflectance signal at 590-610, and 720-780 nanometers allowed discrimination of this chlorophyll signature from those of turbidity (0.66 ≤ r^2 ≤ 0.99).

The widespread use of laser line scanners (LLS) aboard unmanned underwater vehicles in the last decade has opened a unique window to a series of ecological and military applications. Variability of underwater light fields and complexity of light contributions reaching the receiver pose a challenge for target detection of LLS under different environmental conditions. The interference of photons not originating at the target (e.g. water path, bottom) can often be minimized (e.g., time-gated systems) but not excluded. Radiative transfer models were developed to better discriminate noise components from signal contributions at the receiver for two continuous LLS: Real-time Ocean Bottom Optical Topographer (ROBOT) and Fluorescence Imaging Laser Line Scanner (FILLS). Numerical experiments using forward Monte Carlo methods were designed to explore the effects of diverse water turbidities and bottom reflectances on ROBOT and FILLS measurements. Interference due to solar light on LLS target detection was also examined. Reliability of radiative transfer models was tested against standard models (Hydrolight) and aquarium measurements. In general a green laser was the best all around choice to detect targets using both LLS sensors. Based on signal-to-noise (S/N) values, performance of ROBOT for target detection was greater (two-fold) than FILLS because of the lower contribution of path photons in ROBOT than FILLS. When ROBOT was located at 1 m above the target, path radiance contributions (noise) were reduced up to 25-fold in clear waters (0.3 mg m-3) with respect to turbid waters (5 mg m-3). Since ROBOT was more discriminative of bottom reflectance discontinuities (high-contrast transitions) than FILLS, algorithms are proposed to retrieve contrasting man-made targets such mines.