Color is an important cue in object recognition and classification problems. In underwater imager... more Color is an important cue in object recognition and classification problems. In underwater imagery, colors distort due to light propagation through an absorbing and scattering medium. Distortions depend on a number of complex phenomena, the most important being wavelength-dependent absorption and sensitivity of sensors in trichromatic cameras. Using a simplified model of spectral profile for various colored objects, we show by means of numerical simulation that for fixed hardware and medium properties there exist many spectral profiles that lead to different recorded colors in air (without absorption) but the same color in water (with absorption). The above implies that the restoration of true and unique colors from trichromatic underwater imagery is not possible.
Tidally-referenced shoreline data serve a multitude of purposes, ranging from nautical charting, ... more Tidally-referenced shoreline data serve a multitude of purposes, ranging from nautical charting, to coastal change analysis, wetland migration studies, coastal planning, resource management and emergency management. To assess the suitability of the shoreline for a particular application, end users need not only the best available shoreline, but also reliable estimates of the uncertainty in the shoreline position. NOAA’s National Geodetic Survey (NGS) is responsible for mapping the national shoreline depicted on NOAA nautical charts. Previous studies have focused on modeling the uncertainty in NGS shoreline derived from airborne lidar data, but, to date, these methods have not been extended to aerial imagery and photogrammetric shoreline extraction methods, which remain the primary shoreline mapping methods used by NGS. The aim of this study is to develop a rigorous total propagated uncertainty (TPU) model for shoreline compiled from both tide-coordinated and non-tide-coordinated aerial imagery and compiled using photogrammetric methods. The project site encompasses the strait linking Dennys Bay, Whiting Bay and Cobscook Bay in the “Downeast” Maine coastal region. This area is of interest, due to the ecosystem services it provides, as well as its complex geomorphology. The region is characterized by a large tide range, strong tidal currents, numerous embayments, and coarse-sediment pocket beaches. Statistical methods were used to assess the uncertainty of shoreline in this site mapped using NGS’s photogrammetric workflow, as well as to analyze the sensitivity of the mapped shoreline position to a variety of parameters, including elevation gradient in the intertidal zone. The TPU model developed in this work can easily be extended to other areas and may be facilitate estimation of uncertainty in inundation models and marsh migration models
Autowave processes (AWP) can be realized in open kinetic systems which are far from the thermodyn... more Autowave processes (AWP) can be realized in open kinetic systems which are far from the thermodynamic equilibrium. They are manifested by a variety of nonlinear waves, stationary spatial structures, domains, etc. These structures are stable to small fluctuations, independently of the initial and, often, of the boundary conditions. Many well-known phenomena observed in semiconductors with N- and S- shaped volt-ampere characteristics may be attributed to particular cases of AWP.
Different types of transverse instabilities resulting in traveling and motionless spatial structu... more Different types of transverse instabilities resulting in traveling and motionless spatial structures in bistable semiconductor interferometers and injection lasers are investigated on the basis of the proposed generalized theoretical mode
Color is an important cue in object recognition and classification problems. In underwater imager... more Color is an important cue in object recognition and classification problems. In underwater imagery, colors distort due to light propagation through an absorbing and scattering medium. Distortions depend on a number of complex phenomena, the most important being wavelength-dependent absorption and sensitivity of sensors in trichromatic cameras. Using a simplified model of spectral profile for various colored objects, we show by means of numerical simulation that for fixed hardware and medium properties there exist many spectral profiles that lead to different recorded colors in air (without absorption) but the same color in water (with absorption). The above implies that the restoration of true and unique colors from trichromatic underwater imagery is not possible.
Tidally-referenced shoreline data serve a multitude of purposes, ranging from nautical charting, ... more Tidally-referenced shoreline data serve a multitude of purposes, ranging from nautical charting, to coastal change analysis, wetland migration studies, coastal planning, resource management and emergency management. To assess the suitability of the shoreline for a particular application, end users need not only the best available shoreline, but also reliable estimates of the uncertainty in the shoreline position. NOAA’s National Geodetic Survey (NGS) is responsible for mapping the national shoreline depicted on NOAA nautical charts. Previous studies have focused on modeling the uncertainty in NGS shoreline derived from airborne lidar data, but, to date, these methods have not been extended to aerial imagery and photogrammetric shoreline extraction methods, which remain the primary shoreline mapping methods used by NGS. The aim of this study is to develop a rigorous total propagated uncertainty (TPU) model for shoreline compiled from both tide-coordinated and non-tide-coordinated aerial imagery and compiled using photogrammetric methods. The project site encompasses the strait linking Dennys Bay, Whiting Bay and Cobscook Bay in the “Downeast” Maine coastal region. This area is of interest, due to the ecosystem services it provides, as well as its complex geomorphology. The region is characterized by a large tide range, strong tidal currents, numerous embayments, and coarse-sediment pocket beaches. Statistical methods were used to assess the uncertainty of shoreline in this site mapped using NGS’s photogrammetric workflow, as well as to analyze the sensitivity of the mapped shoreline position to a variety of parameters, including elevation gradient in the intertidal zone. The TPU model developed in this work can easily be extended to other areas and may be facilitate estimation of uncertainty in inundation models and marsh migration models
Autowave processes (AWP) can be realized in open kinetic systems which are far from the thermodyn... more Autowave processes (AWP) can be realized in open kinetic systems which are far from the thermodynamic equilibrium. They are manifested by a variety of nonlinear waves, stationary spatial structures, domains, etc. These structures are stable to small fluctuations, independently of the initial and, often, of the boundary conditions. Many well-known phenomena observed in semiconductors with N- and S- shaped volt-ampere characteristics may be attributed to particular cases of AWP.
Different types of transverse instabilities resulting in traveling and motionless spatial structu... more Different types of transverse instabilities resulting in traveling and motionless spatial structures in bistable semiconductor interferometers and injection lasers are investigated on the basis of the proposed generalized theoretical mode
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Papers by Yuri Rzhanov