Light field

About: Light field is a research topic. Over the lifetime, 5357 publications have been published within this topic receiving 87424 citations.

An asymptotic closure theory for irradiance in the sea and its inversion to obtain the inherent optical properties

Abstract: An expression is derived for the rate at which the diffuse attenuation coefficient for vector irradiance approaches its asymptotic value in a homogeneous medium. The asymptotic approach rate is shown to be a function of boundary conditions at the surface and the asymptotic diffuse attenuation coefficient which is an inherent optical property. The asymptotic approach rate is then used to derive the vertical structure of the vector and scalar irradiances, the vector and scalar diffuse attenuation coefficients, the average cosine of the light field, and the remotely sensed reflectance at the surface, based only on the surface values of the vector and scalar irradiances and the vector and scalar diffuse attenuation coefficients. This theory is inverted and combined with previously derived radiative transfer relations to show that in principle the vertical structure of the absorption, scattering, attenuation, and backscattering coefficients can be derived from the vertical structure of the scalar and vector irradiances and the nadir radiance. An example for the western North Atlantic Ocean is provided. The vertical structure of the light in the sea is important to many disciplines. Sunlight is the energy source for the biological food chain, and the amount and spectrum of solar energy available at a given depth must be known if accurate productivity calculations are to be made. The oceanic biota in return are a major factor in determining the distribution of light through their absorption and scattering characteristics. Solar energy that is absorbed by the ocean plays a role in physical oceanography, in particular in the structure of the mixed layer. Optical remote sensing allows us to study the large-scale structure of biological and optical parameters by measuring radiance emanating from the ocean. Remote sensing is essential in investigating the global effects of stratospheric ozone depletion and the greenhouse effect. The behavior of the light field in the sea is described by the equation of radiative

Light Field Analysis for Modeling Image Formation

Abstract: Image formation is traditionally described by a number of individual models, one for each specific effect in the image formation process. However, it is difficult to aggregate the effects by concatenating such individual models. In this paper, we apply light transport analysis to derive a unified image formation model that represents the radiance along a light ray as a 4-D light field signal and physical phenomena such as lens refraction and blocking as linear transformations or modulations of the light field. This unified mathematical framework allows the entire image formation process to be elegantly described by a single equation. It also allows most geometric and photometric effects of imaging, including perspective transformation, defocus blur, and vignetting, to be represented in both 4-D primal and dual domains. The result matches that of traditional models. Generalizations and applications of this theoretic framework are discussed.

Reconstructing the indirect light field for global illumination

Abstract: Stochastic techniques for rendering indirect illumination suffer from noise due to the variance in the integrand. In this paper, we describe a general reconstruction technique that exploits anisotropy in the light field and permits efficient reuse of input samples between pixels or world-space locations, multiplying the effective sampling rate by a large factor. Our technique introduces visibility-aware anisotropic reconstruction to indirect illumination, ambient occlusion and glossy reflections. It operates on point samples without knowledge of the scene, and can thus be seen as an advanced image filter. Our results show dramatic improvement in image quality while using very sparse input samplings.