نتایج جستجو برای: radiance

تعداد نتایج: 3741  

Journal: :Applied optics 2006
Steven W Brown George P Eppeldauer Keith R Lykke

Detectors have historically been calibrated for spectral power responsivity at the National Institute of Standards and Technology by using a lamp-monochromator system to tune the wavelength of the excitation source. Silicon detectors can be calibrated in the visible spectral region with combined standard uncertainties at the 0.1% level. However, uncertainties increase dramatically when measurin...

Journal: :Optics express 2015
Jianwei Wei Zhongping Lee Marlon Lewis Nima Pahlevan Michael Ondrusek Roy Armstrong

The radiance transmittance (Tr) is the ratio of the water-leaving radiance (Lw(0+)) to the sub-surface upwelling radiance (Lu(0-)), which is an important optical parameter for ocean optics and ocean color remote sensing. Historically, a constant value (~0.54) based on theoretical presumptions has been adopted for Tr and is widely used. This optical parameter, however, has never been measured in...

2007
KAVITA BALA JULIE DORSEY SETH TELLER

Ray tracing, which computes radiance, is usually regarded as an off-line rendering algorithm that is too slow for interactive use. In this paper, we present a system that uses per-surface four-dimensional interpolants to approximate radiance, while providing guaranteed error bounds. Our system exploits object-space, ray-space, image-space and temporal coherence to accelerate ray tracing. Our sy...

1996
Seth J. Teller Kavita Bala Julie Dorsey

Classical ray-tracing algorithms compute radiance returning to the eye along one or more sample rays through each pixel of an image. The output of a ray-tracing algorithm, although potentially photorealistic, is a two-dimensional quantity { an image array of radiance values { and is not directly useful from any viewpoint other than the one for which it was computed. This paper makes several con...

2003
Zhen Wen Zicheng Liu Thomas S. Huang

A radiance environment map pre-integrates a constant surface reflectance with the lighting environment. It has been used to generate photo-realistic rendering at interactive speed. However, one of its limitations is that each radiance environment map can only render the object which has the same surface reflectance as what it integrates. In this paper, we present a ratio-image based technique t...

2009
Taemin Kim Ara V. Nefian Michael Broxton

The topographical and photometric reconstruction of the moon from Apollo metric data has gained attention to support manned mission planning since the NASA has been working on return to the moon in 2004. This paper focuses on photometric recovery of the moon surface from Apollo orbital imagery. The statistical behavior of photons generates the scene radiance which follows a continuous Poisson d...

2009
A. Marshak Y. Knyazikhin J. C. Chiu W. J. Wiscombe

[1] The ARM Shortwave Spectrometer (SWS) measures zenith radiance at 418 wavelengths between 350 and 2170 nm. Because of its 1-sec sampling resolution, the SWS provides a unique capability to study the transition zone between cloudy and clear sky areas. A spectral invariant behavior is found between ratios of zenith radiance spectra during the transition from cloudy to cloud-free. This behavior...

2001
Steve Kacenjar Steve Esposito

Atmospheric profile variability impacts the effectiveness of hyperspectral remote sensing systems to identify geological materials from space. This variability alters the "truth" spectrum (e.g. reflective or emissive) by modifying its spectrum through such atmospheric factors as transmissivity, upwelling radiance, and downwelling radiance. Incomplete characterization of these effects can lead t...

Journal: :Medical ultrasonography 2016
Francisco Raga Sara Cholvi Maria José Esquembre Diana Boigues Carolina Lucas Fernando Bonilla-Musoles

In this case report the diagnosis of a uterine lipoleiomyoma is depicted by means of a three-dimensional radiance mode. The advent of radiance or silhouette mode as a new tool in ultrasound diagnosis is intended to assist by generating additional realistic image visualization and a better distinction among different tissues.

2013
Juha-Matti Hirvonen Liisa Halonen

ii Abstract (in Finnish) iiiin Finnish) iii

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