| Perception of illumination direction in images of 3-D convex objects: influence of surface materials and light fields. | |
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MedLine Citation:
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PMID: 16836054 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We investigated the perception of illumination direction in images of 3-D convex objects under variations of light field and surface material properties. In a first experiment, we used an illumination-matching procedure in order to measure observers' ability to estimate the direction of illumination in images of 3-D polyhedra rendered under different light fields and illumination directions. Match deviations were larger in frontal direction than in rear directions, mainly counterclockwise in azimuth component, and diverged, in elevation component, from the image plane. In a second experiment, we examined whether the direction estimate was affected by the surface material type (BRDF), the light field, and the illumination direction. Angular deviations varied with material surface type and were largest in the test elevation direction 0 degrees. Elevation component deviations also differed with surface type and were larger in hemispherical diffuse lighting than in collimated lighting. These results suggest that the direction estimation is better with images of evenly distributed intensity gradients than with those of drastically varying gradients, and that the visual system may not take intensity variations due to the surface material or the light field into account in estimating the direction of illumination. |
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Authors:
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Byung-Geun Khang; Jan J Koenderink; Astrid M L Kappers |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Perception Volume: 35 ISSN: 0301-0066 ISO Abbreviation: Perception Publication Date: 2006 |
Date Detail:
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Created Date: 2006-07-13 Completed Date: 2006-10-10 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0372307 Medline TA: Perception Country: England |
Other Details:
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Languages: eng Pagination: 625-45 Citation Subset: IM |
Affiliation:
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Department of Physics of Man, Helmholtz Institute, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands. bgkhang@sunyopt.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Cues Depth Perception Humans Light Lighting* Mathematics Orientation Pattern Recognition, Visual Photic Stimulation / methods Psychophysics Scattering, Radiation Surface Properties Visual Perception* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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