Many real-life materials have sparkling appearances.Some small flakes on the surface of an object can make a considerable contribution by reflecting or refracting light at a particular angle,eventually causing a spark...Many real-life materials have sparkling appearances.Some small flakes on the surface of an object can make a considerable contribution by reflecting or refracting light at a particular angle,eventually causing a sparkling appearance.Most existing approaches have focused on the glinty effects on reflective surfaces.However,transparent glint rendering has not been well studied,even though there are many natural phenomena(e.g.,frost)in the real world.Recent studies have proposed the simulation of transparent glints under specific constraints(e.g.,limited to the Beckmann distribution and V-groove shadowing-masking function).In this study,we propose a more general transparent glint model by performing a four-dimensional hierarchical search to count the particles located in the pixel footprint and cone around the refracted ray.Our method can produce transparent glint appearances for arbitrary normal distribution functions(e.g.,GGX or Beckmann)and converge to a smooth microfacet model with a large particle count.展开更多
The theoretical implementation aspects of scattered field prediction and angular glint calculation in near-field region are proposed in this work.First of all,a more refined expression of the Green function is develop...The theoretical implementation aspects of scattered field prediction and angular glint calculation in near-field region are proposed in this work.First of all,a more refined expression of the Green function is developed.In this representation,an expansion center is adopted within the neighborhood of the sources.Then a high-frequency electromagnetic scattering evaluation algorithm is formulated,combining the refined physical optics(PO)and equivalent edge current(EEC)algorithm.The modified method not only retains the conciseness and efficiency of the standard code but also can be directly used in the near field(NF)scattering estimation.Afterwards,two basic concepts of the angular glint are briefly introduced and formulated.The proposed procedure makes preparation for the computation of NF linear deviation.Numerical examples demonstrate the accuracy and efficiency of the NF scattering prediction algorithm.The angular glint characteristics in near-field scenarios are also presented and analyzed in the final section.展开更多
In radar target tracking application, the observation noise is usually non-Gaussian, which is also referred as glint noise. The performances of conventional trackers degra de severely in the presence of glint noise. A...In radar target tracking application, the observation noise is usually non-Gaussian, which is also referred as glint noise. The performances of conventional trackers degra de severely in the presence of glint noise. An improved particle filter, Markov chain Monte Carlo particle filter (MCMC-PF), is applied to cope with radar target tracking when the measurements are perturbed by glint noise. Tracking performance of the filter is demonstrated in the present of glint noise by computer simulation.展开更多
Angular glint can be interpreted as a distortion of the radar echo signal phase front, or alternatively, a tilt of the direction of energy flow from the radial direction. As the complementarities and support of argume...Angular glint can be interpreted as a distortion of the radar echo signal phase front, or alternatively, a tilt of the direction of energy flow from the radial direction. As the complementarities and support of argumentation in our previous work, a general discussion about two concepts of angular glint is made based on electromagnetic theory to demonstrate that these two concepts are equivalent when geometrical optics approximation is used and＇ the receiving antenna is linearly polarized.展开更多
The angular glint in the near field plays an important role on radar tracking errors. To predict it more efficiently for electrically large targets, a new method based on graphical electromagnetic computing （GRECO） ...The angular glint in the near field plays an important role on radar tracking errors. To predict it more efficiently for electrically large targets, a new method based on graphical electromagnetic computing （GRECO） is proposed. With the benefit of the graphic card, the GRECO prediction method is faster and more accurate than other methods. The proposed method at the first time considers the special case that the targets cannot be completely covered by radar beams, which makes the prediction of radar tracking errors more self-contained in practical circumstances. On the other hand, the process of the scattering center extraction is omitted, resulting in possible angular glint prediction in real time. Comparisons between the simulation results and the theoretical ones validate its correctness and value to academic research and engineering applications.展开更多
This paper presents a method to analyze and calculate the angular glint of targets. By parting the target to very small size cells, using high-frequency approximation, the near-field radar cross section （RCS） is cal...This paper presents a method to analyze and calculate the angular glint of targets. By parting the target to very small size cells, using high-frequency approximation, the near-field radar cross section （RCS） is calculated based on the scattering from complex targets and environments （SCTE） system, and the angular glint is calculated by the phase grads. The results show that the angular glint can be calculated exactly in the SCTE system, and this method is correct and efficient. In the near-zone, the far-field theory is not applicable and the angular glint should be calculated by the near-field theory.展开更多
Shallow marine sand waves are formed on the seabed and are widely distributed within tidal environments.However,the use of multibeam echo sounding(MBES)is costly to obtain the bathymetric mapping of large complex sand...Shallow marine sand waves are formed on the seabed and are widely distributed within tidal environments.However,the use of multibeam echo sounding(MBES)is costly to obtain the bathymetric mapping of large complex sand waves.Therefore,we propose a new method that employs a combination of multiangle sun glint images and sparse MBES data to achieve comprehensive bathymetric mapping of large and complex sand waves.This method involves estimating sea surface roughness,automatically extracting sand-wave crests,conducting adaptive subregion partitioning,estimating the water depth at auxiliary points,and generating digital bathymetric models.The method was employed in a case study of sand waves on the Taiwan Bank.Bathymetric mapping was implemented for large complex sand waves over an area spanning approximately 350 km~2 using multiangle sun glint images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer and MBE S data.The results show that mapped and measured water depths were well-matched;the root-mean-square error of water depths was 1.77 m,and the relative error was 5.03%.These findings show that bathymetric mapping of large complex sand waves can be effectively conducted using the new method,and as such,the workload of MBES is reduced and efficiency is improved.展开更多
From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering ec...From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering echo relative phase versus incident angles. A representative vector model of N-point target consisting of N anisotropic point scatterers has been proposed to reveal the inherent law implied by the experimental phenomenon. Analytical arguments then demonstrate that, under certain conditions the equivalence can be found between the backward angular glint and the derivative of backscattering echo relative phase with respect to incident angles. This work is of particular value in deriving angular glint from backscattering measurement in the case of no bistatic scattering measurement capability.展开更多
The purpose of this study was to examine the behavioral impact of varying LED （light emitting diode） spectral emissions on avian species. A novel oculo-neuro-motor response to monochromatic LEDs has been identified....The purpose of this study was to examine the behavioral impact of varying LED （light emitting diode） spectral emissions on avian species. A novel oculo-neuro-motor response to monochromatic LEDs has been identified. LED colored light of sufficient intensity matched to the short-wavelength cones of avian species can efficiently diminish overall visual perception leading to an augmented behavioral response. The study method involved monitoring the change in behavioral response after exposure to high brightness monochromatic LED light to wild Osprey （Pandion haliaetus） foraging and nesting in their natural environment. Our results demonstrated a statistically significant change in foraging behaviors with wild Osprey （p = 0.005） and in nesting behavior as a result of exposure to high brightness monochromatic LED light. An augmented behavioral responses was observed which is believed to be analogous to human reaction to solar glare and glint. The neuroimaging mechanism of avian species is discussed. This novel augmented behavioral response provides a new technique of studying the neuroscience of temporal and spatial light stimulus. A non-lethal deterrence technique involving the augmented behavioral response could mitigate mortality and morbidity of avian-human conflict in areas such as airports, airplane bird strikes, and wind turbines.展开更多
基金supported by the National Key R&D Program of China under Grant No.2022ZD0116305the National Natural Science Foundation of China underGrant Nos.62172220 and 62272275.
文摘Many real-life materials have sparkling appearances.Some small flakes on the surface of an object can make a considerable contribution by reflecting or refracting light at a particular angle,eventually causing a sparkling appearance.Most existing approaches have focused on the glinty effects on reflective surfaces.However,transparent glint rendering has not been well studied,even though there are many natural phenomena(e.g.,frost)in the real world.Recent studies have proposed the simulation of transparent glints under specific constraints(e.g.,limited to the Beckmann distribution and V-groove shadowing-masking function).In this study,we propose a more general transparent glint model by performing a four-dimensional hierarchical search to count the particles located in the pixel footprint and cone around the refracted ray.Our method can produce transparent glint appearances for arbitrary normal distribution functions(e.g.,GGX or Beckmann)and converge to a smooth microfacet model with a large particle count.
文摘The theoretical implementation aspects of scattered field prediction and angular glint calculation in near-field region are proposed in this work.First of all,a more refined expression of the Green function is developed.In this representation,an expansion center is adopted within the neighborhood of the sources.Then a high-frequency electromagnetic scattering evaluation algorithm is formulated,combining the refined physical optics(PO)and equivalent edge current(EEC)algorithm.The modified method not only retains the conciseness and efficiency of the standard code but also can be directly used in the near field(NF)scattering estimation.Afterwards,two basic concepts of the angular glint are briefly introduced and formulated.The proposed procedure makes preparation for the computation of NF linear deviation.Numerical examples demonstrate the accuracy and efficiency of the NF scattering prediction algorithm.The angular glint characteristics in near-field scenarios are also presented and analyzed in the final section.
文摘In radar target tracking application, the observation noise is usually non-Gaussian, which is also referred as glint noise. The performances of conventional trackers degra de severely in the presence of glint noise. An improved particle filter, Markov chain Monte Carlo particle filter (MCMC-PF), is applied to cope with radar target tracking when the measurements are perturbed by glint noise. Tracking performance of the filter is demonstrated in the present of glint noise by computer simulation.
文摘Angular glint can be interpreted as a distortion of the radar echo signal phase front, or alternatively, a tilt of the direction of energy flow from the radial direction. As the complementarities and support of argumentation in our previous work, a general discussion about two concepts of angular glint is made based on electromagnetic theory to demonstrate that these two concepts are equivalent when geometrical optics approximation is used and＇ the receiving antenna is linearly polarized.
基金supported by the National Natural Science Foundation of China (60871069)
文摘The angular glint in the near field plays an important role on radar tracking errors. To predict it more efficiently for electrically large targets, a new method based on graphical electromagnetic computing （GRECO） is proposed. With the benefit of the graphic card, the GRECO prediction method is faster and more accurate than other methods. The proposed method at the first time considers the special case that the targets cannot be completely covered by radar beams, which makes the prediction of radar tracking errors more self-contained in practical circumstances. On the other hand, the process of the scattering center extraction is omitted, resulting in possible angular glint prediction in real time. Comparisons between the simulation results and the theoretical ones validate its correctness and value to academic research and engineering applications.
基金Supported by the National Natural Science Foundation of China (60301007)the Chen-Guang Plan of Wuhan City(20055003059-32)
文摘This paper presents a method to analyze and calculate the angular glint of targets. By parting the target to very small size cells, using high-frequency approximation, the near-field radar cross section （RCS） is calculated based on the scattering from complex targets and environments （SCTE） system, and the angular glint is calculated by the phase grads. The results show that the angular glint can be calculated exactly in the SCTE system, and this method is correct and efficient. In the near-zone, the far-field theory is not applicable and the angular glint should be calculated by the near-field theory.
基金Supported by the National Natural Science Foundation of China(Nos.41876208,41830540,41576174)。
文摘Shallow marine sand waves are formed on the seabed and are widely distributed within tidal environments.However,the use of multibeam echo sounding(MBES)is costly to obtain the bathymetric mapping of large complex sand waves.Therefore,we propose a new method that employs a combination of multiangle sun glint images and sparse MBES data to achieve comprehensive bathymetric mapping of large and complex sand waves.This method involves estimating sea surface roughness,automatically extracting sand-wave crests,conducting adaptive subregion partitioning,estimating the water depth at auxiliary points,and generating digital bathymetric models.The method was employed in a case study of sand waves on the Taiwan Bank.Bathymetric mapping was implemented for large complex sand waves over an area spanning approximately 350 km~2 using multiangle sun glint images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer and MBE S data.The results show that mapped and measured water depths were well-matched;the root-mean-square error of water depths was 1.77 m,and the relative error was 5.03%.These findings show that bathymetric mapping of large complex sand waves can be effectively conducted using the new method,and as such,the workload of MBES is reduced and efficiency is improved.
文摘From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering echo relative phase versus incident angles. A representative vector model of N-point target consisting of N anisotropic point scatterers has been proposed to reveal the inherent law implied by the experimental phenomenon. Analytical arguments then demonstrate that, under certain conditions the equivalence can be found between the backward angular glint and the derivative of backscattering echo relative phase with respect to incident angles. This work is of particular value in deriving angular glint from backscattering measurement in the case of no bistatic scattering measurement capability.
基金This work was supported by grant No. IIP-1350562 from the National Science Foundation. NH Audubon Society provided assistance in tabulating the field results. Support at the test sites was provided by US Cellular, and NH Fish and Game Department--Milford Fish Hatchery.
文摘The purpose of this study was to examine the behavioral impact of varying LED （light emitting diode） spectral emissions on avian species. A novel oculo-neuro-motor response to monochromatic LEDs has been identified. LED colored light of sufficient intensity matched to the short-wavelength cones of avian species can efficiently diminish overall visual perception leading to an augmented behavioral response. The study method involved monitoring the change in behavioral response after exposure to high brightness monochromatic LED light to wild Osprey （Pandion haliaetus） foraging and nesting in their natural environment. Our results demonstrated a statistically significant change in foraging behaviors with wild Osprey （p = 0.005） and in nesting behavior as a result of exposure to high brightness monochromatic LED light. An augmented behavioral responses was observed which is believed to be analogous to human reaction to solar glare and glint. The neuroimaging mechanism of avian species is discussed. This novel augmented behavioral response provides a new technique of studying the neuroscience of temporal and spatial light stimulus. A non-lethal deterrence technique involving the augmented behavioral response could mitigate mortality and morbidity of avian-human conflict in areas such as airports, airplane bird strikes, and wind turbines.
