Hybrid numerical method for solution of the radiative transfer equation in one, two, or three dimensions

Reinersman, Phillip N.; Carder, Kendall L.

doi:10.1364/ao.43.002734

Cited by 15 publications

(19 citation statements)

References 8 publications

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“…2-D and 3-D environmental optical models have been developed (Reinersman and Carder 2004) and tested that calculate the radiance field in all three directions with ca. 5-10 degree angular and 12.5 cm spatial resolutions.…”

Section: Resultsmentioning

confidence: 99%

“…5-10 degree angular and 12.5 cm spatial resolutions. The feasibility of observing the ROBOT laser fan beam on the bottom of a ship hull in daylight from various ranges can be determined (Reinersman and Carder 2004;Carder et al 2005;. The greater the range, the faster a hull can be inspected using a fan beam.…”

Section: Resultsmentioning

confidence: 99%

“…HyMOM models of one, two, and three dimensions have been developed and applied to modeling of natural light fields about ridges and trenches and beneath ships (2-D; Reinersman and Carder, 2004) and around pilings (3-D small environment; Carder et al 2005). Extension of HyMOM to 2 wavelengths (305 nm and 532 nm) and a larger 3-D field (10m x 10m x 5m) with a 5m cubic object (e.g.…”

Section: Work Completedmentioning

confidence: 99%

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Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls

Carder¹,

Reinersman²

2006

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LONG-TERM GOALSThe long-term goal of this research effort is to develop a method to predict the visible and ultraviolet radiance distribution in complex three-dimensional marine environments as found in ports, anchorages, and coastal waters. Effective deployment of AUV-or ROV-mounted sensors to inspect ship hulls and port facilities will depend on accurate, real-time prediction of the sub-surface optical environment at the time and place of inspection. Furthermore, since the active or passive camouflaging of divers, AUVs, and bottom objects is quite dependent upon masking the effects of three-dimensionality, 3-D optical models to evaluate such problems are being developed and implemented. While HyMOM will be used to calculate light fluxes to the bottom for foreign-object detection near structures such as coral heads, seawalls, and pilings, it is equally useful in ecological models dealing with the bleaching of corals and foraminifera and the photosynthesis of benthic plants. OBJECTIVESThe initial objective of this work is to extend the existing model system from two-dimensional environments into realistic three-dimensional environments. The model concept involves four distinct phases: 1) Modeling the optical response of individual three-dimensional elements using Monte Carlo techniques, analytic expressions, and ad-hoc definitions; 2) Building the three-dimensional region to be modeled by combining the elements developed in the previous phase; 3) Determining the radiance field around each element of the modeled environment by employing an iterative, relaxation technique to diffuse the source radiance throughout the environment; 4) Displaying the results of the model numerically and graphically. The final objectives are to evaluate and validate the model results with field radiance and irradiance data for a variety of settings, and to apply the model to predicting the perceptibility of underwater objects for all angles and fields of view. APPROACHConsider a point, ρ i , on the surface of an arbitrary region (Fig. 1). This point is being illuminated by a pencil of radiant power, E i , at wavelength λ i and from direction ε i . E i is that portion of the irradiance at ρ i that arrives from direction ε i , expressed in units W m -2 sr -1 . As a result of this illumination, pow may be emitted from the region at wavelength λ er o , point ρ o , and direction ε o . In the following

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Work Completedmentioning

confidence: 99%

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Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls

Carder¹,

Reinersman²

2006

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“…Here, we show finely-sampled DIRSIG results of the upwelling radiance L u , the upwelling scalar irradiance E ou , and the downwelling irradiance E d , compared to the mean predicted values from [7]. Fig.4 likewise compares DIRSIG simulated downwelling irradiance to that predicted by an independent numerical code [8], but for a more taxing 3D scenario that leverages the benefit of using a photon mapped solution. A complete description of the scenario and its independent solution are described elsewhere [8].…”

Section: Mediummentioning

confidence: 89%

Validation of in-water 3D radiative transfer using DIRSIG

Speir

Schott

Goodenough

et al. 2010

2010 2nd Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing

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Sensor reaching radiance in coastal ocean-water environments contains contributions from the air-water interface, in-water objects, and the participating volume itself. If rendered by a forward-modeling synthetic image generation program, the imagery must account for several interesting phenomenon, including, but not limited to; volumetric scattering, shadows, skyfraction, background reflections, and capillary and gravity wave glints and caustics. DIRSIG models the radiative transfer process in this complex environment using a combination of sophisticated raytracing and photon mapping techniques. This research illustrates a subset of our validation efforts associated with the forward radiometric modeling process used by DIRSIG when rendering coastal environments with significant contributions from in-water objects. The results exemplify DIRSIG's ability to render spectrally independent (elastic) and radiometrically accurate hyperspectral imagery of participating media.

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“…The initial objective of this work is to extend the existing 3-D Hybrid Marine Optical Model (HyMOM) (Reinersman and Carder 2004;Carder et al, 2005; Carder and Reinersman, 2007) to determine the three-dimensional light structure of representative marine environments in order to calculate the character of the radiance field needed to remove asset contrast with the background. A secondary objective is to develop a practical method to provide the additional radiance necessary to accomplish this task and to make the asset "self-aware" of its background contrast.…”

Section: Objectivesmentioning

confidence: 99%

Active Camouflage of Underwater Assets (ACUA)

Carder¹,

Reinersman²

2007

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LONG-TERM GOALSThe long-term goals of this research are to develop the control methodology for active cloaking of underwater assets and the initial hardware concepts to test the proposed cloaking approach. This work is a natural extension of ONR Project N00014-02-1-0211 (Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls) where the perceptibility of underwater assets was modeled. OBJECTIVESThe initial objective of this work is to extend the existing 3-D Hybrid Marine Optical Model (HyMOM) (Reinersman and Carder 2004;Carder et al, 2005; Carder and Reinersman, 2007) to determine the three-dimensional light structure of representative marine environments in order to calculate the character of the radiance field needed to remove asset contrast with the background. A secondary objective is to develop a practical method to provide the additional radiance necessary to accomplish this task and to make the asset "self-aware" of its background contrast. Only in this manner will the asset be able to change radiance fields with environmental conditions. APPROACHOur approach rests on the foundation of our knowledge of how light interacts with water and the bottom and how it is spectrally and spatially transformed before it can become water-leaving radiance L u . The mechanism for actively controlling submarine "cloaking" will be to use our 3-D Hybrid Marine Optical Model (HyMOM) to understand the spatial structure (e.g. Q factor, etc.) of various natural waters and a measurement methodology to control the brightness of light sources strategically placed to minimize contrast. The importance of this predictive knowledge is significant since L u is the background from which a submerged object needs to be distinguished by an in-water or air-borne sensor, and the amount of infilling of upwelling radiance occluded by a submersible (e.g. AUV; SEAL Delivery Vehicle) will need to be added to that fraction of down-welling irradiance reflected up from the vehicle. Armed with that predictive knowledge, we propose to demonstrate that hybrid, electrooptic "chromaphotophores", that is, spectral-photophores can be utilized to provide active cloaking, and that the asset can be made "self aware" of its contrast relative to the background. HyMOM will be 1

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Hybrid numerical method for solution of the radiative transfer equation in one, two, or three dimensions

Cited by 15 publications

References 8 publications

Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls

Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls

Validation of in-water 3D radiative transfer using DIRSIG

Active Camouflage of Underwater Assets (ACUA)

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