A semi-empirical model for the Fourier synthesis of deepwater, wind-wave scenes has been constructed for the analysis of water-wave slope spectra. The main simplifying assumptions of this model are 1) fully-developed wind-wave surfaces are quasi-homogeneous, quasi -stationary and are therefore treatable by Fourier methods, 2) the subsurface is both optically and mechanically deep, and 3) the small range of spectral wave components defines a fetch-limited, small amplitude condition. A nonlinear transformation of wave slope to reflected and refracted radiance in both horizontal and vertical polarizations was effected under the special conditions of Brewster-angle viewing under clear skies at a spectral wavelength of 460 nanometers. Seventy two syntheses were varied with respect to six distinct solar positions, four distinct wind directions, and three distinct wind velocities. The synthetic wave scenes were analyzed via the forward Fourier transformation and their radiance magnitude spectra were compared with the original slope magnitude spectra of the initial synthesis in order to estimate the effects of the nonlinear radiance transformation on the recovery of the wave slope spectrum from imagery. Within the boundaries of this study, it was determined that 1) the limited results of Chapman and Irani  have been generally verified, 2) the existence of an optimal imaging geometry for slope spec trum estimation is indicated, and 3) the presence of subresolution wave slopes creates a significant effect on wave slope spectra derived from imagery.
Library of Congress Subject Headings
Oceanography--Remote sensing--Congresses; Fourier transform optics; Ocean waves; Image processing--Digital techniques--Evaluation
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
North, Jan Arthur, "Fourier image synthesis and slope spectrum analysis of deepwater, wind-wave scenes viewed at Brewster's angle" (1989). Thesis. Rochester Institute of Technology. Accessed from
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