Correlated pairs of photons can be used to access what is effectively an omnipresent absolute standard of spectral radiance. The process of spontaneous parametric downconversion, in which pump photons are converted into pairs of photons, can be thought of as being stimulated by an omnipresent and omnidirectional one photon per mode vacuum background. This background has units of spectral radian...

The upwelling radiance distribution in optically shallow water is investigated with experiments and Hydrolight numerical simulations for two different benthic surfaces and a range of solar zenith angles (,608). Over a bright sand surface (water depth 5 m) the upwelling radiance distribution was brightest at nadir and decreased toward the horizon. The upwelling radiance distribution was nearly a...

An experimental investigation of ir sky radiance and radiance fluctuations in the 8-13-micro atmospheric window is reported. Measurements were made with ground-based, filtered bolometer detector radiometers under clear sky and cirrus overcast conditions. Sky radiance was measured very close to the limb of the sun to permit detection of the solar aureole caused by forward scattering by cirrus ic...

A laboratory experiment was designed to determine the spectral characteristics of different types of sediment suspended in water in the visible and near infrared wavelengths (0.45-0.9 /xm) using a fourchannel radiometer. Field collected sediments were resuspended in water to produce different concentration levels for the measurement of radiance. Spectral measurements of turbid water showed a di...

Topography affects the fraction of direct and diffuse radiation received on a pixel and changes the sun–target–sensor geometry, resulting in variations in the observed radiance. Retrieval of surface–atmosphere properties from top of atmosphere radiance may need to account for topographic effects. This study investigates how such effects can be taken into account for top of atmosphere radiance m...

We consider the problem of estimating the shape and radiance of a scene from a calibrated set of images under the assumption that the scene is Lambertian and its radiance is piecewise constant. We model the radiance segmentation explicitly using smooth curves on the surface that bound regions of constant radiance. We pose the scene reconstruction problem in a variational framework, where the un...

Introduction Blue light is a part of the spectrum with the highest energy content, which can reach the retina. The damage that it can cause to the retina is called photochemical or blue-light retinal injury. For the retinal injury assessment of the photochemical and aphakic retinal hazards in the wavelength range of 300-700 nm, use of effective spectral radiance limits (W.m-2.sr-1) seems to be...

Shape from shading schemes are based on the assumption that image radiance is a function of surface normal alone. Unfortunately, because surfaces illuminate one another, radiance is a complicated global property of surface shape. We review briefly the equations governing mutual illumination effects, and demonstrate that mutual illumination forms a major component of image radiance. We then disc...