Document Detail

Light field constancy within natural scenes.
MedLine Citation:
PMID:  17932545     Owner:  NLM     Status:  PubMed-not-MEDLINE    
The structure of light fields of natural scenes is highly complex due to high frequencies in the radiance distribution function. However it is the low-order properties of light that determine the appearance of common matte materials. We describe the local light field in terms of spherical harmonics and analyze the qualitative properties and physical meaning of the low-order components. We take a first step in the further development of Gershun's classical work on the light field by extending his description beyond the 3D vector field, toward a more complete description of the illumination using tensors. We show that the three first components, namely, the monopole (density of light), the dipole (light vector), and the quadrupole (squash tensor) suffice to describe a wide range of qualitatively different light fields. In this paper we address a related issue, namely, the spatial properties of light fields within natural scenes. We want to find out to what extent local light fields change from point to point and how different orders behave. We found experimentally that the low-order components of the light field are rather constant over the scenes whereas high-order components are not. Using very simple models, we found a strong relationship between the low-order components and the geometrical layouts of the scenes.
Alexander A Mury; Sylvia C Pont; Jan J Koenderink
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Applied optics     Volume:  46     ISSN:  0003-6935     ISO Abbreviation:  Appl Opt     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-10-12     Completed Date:  2008-01-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0247660     Medline TA:  Appl Opt     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7308-16     Citation Subset:  -    
Department of Physics and Astronomy, Physics of Man, Helmholtz Institute, Utrecht University Princetonplein 5, NL 3584 CC Utrecht, The Netherlands.
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