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Titolo:
On the relationship between radiance and irradiance: Determining the illumination from images of a convex Lambertian object
Autore:
Ramamoorthi, R; Hanrahan, P;
Indirizzi:
Stanford Univ, Dept Comp Sci, Stanford, CA 94305 USA Stanford Univ Stanford CA USA 94305 Dept Comp Sci, Stanford, CA 94305 USA
Titolo Testata:
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION
fascicolo: 10, volume: 18, anno: 2001,
pagine: 2448 - 2459
SICI:
1084-7529(200110)18:10<2448:OTRBRA>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Ramamoorthi, R Stanford Univ, Dept Comp Sci, Gates Wing 3B-386, Stanford, CA 94305 USA Stanford Univ Gates Wing 3B-386 Stanford CA USA 94305 5 USA
Citazione:
R. Ramamoorthi e P. Hanrahan, "On the relationship between radiance and irradiance: Determining the illumination from images of a convex Lambertian object", J OPT SOC A, 18(10), 2001, pp. 2448-2459

Abstract

We present a theoretical analysis of the relationship between incoming radiance and irradiance. Specifically, we address the question of whether it is possible to compute the incident radiance from knowledge of the irradiance at all surface orientations This is a fundamental question in computer vision and inverse radiative transfer. We show that the irradiance can be viewed as a simple convolution of the incident illumination, i.e., radiance and a clamped cosine transfer function. Estimating the radiance can then be seen as a deconvolution operation. We derive a simple closed-form formula for the irradiance in terms of spherical harmonic coefficients of the incident illumination and demonstrate. that the odd-order modes of the lighting with order greater than 1 are completely annihilated. Therefore. these components cannot be estimated from the irradiance, contradicting a theorem that is due to Preisendorfer. A practical realization of the radiance-from-irradiance problem is the estimation of the lighting,from, images of a homogeneous convex curved Lambertian surface of known geometry under distant illumination, since a Lambertian object reflects light equally in all directions proportional to the irradiance. We briefly discuss practical and physical considerations and describe a simple experimental test to verify our theoretical results. (C) 2001 Optical Society of America.

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Documento generato il 29/09/20 alle ore 06:44:44