NDLI: Estimation of multiple directional light sources for synthesis of mixed reality images

Content Provider	IEEE Xplore Digital Library
Author	Yang Wang Samaras, D.
Copyright Year	2002
Description	Author affiliation: Dept. of Comput. Sci., State Univ. of New York, Stony Brook, NY, USA (Yang Wang; Samaras, D.)
Abstract	We present a new method for the detection and estimation of multiple directional illuminants, using a single image of any object with known geometry and Lambertian reflectance. We use the resulting highly accurate estimates to modify virtually the illumination and geometry of a real scene and produce correctly illuminated mixed reality images. Our method obviates the need to modify the imaged scene by inserting calibration objects of any particular geometry, relying instead on partial knowledge of the geometry of the scene. Thus, the recovered multiple illuminants can be used both for image-based rendering and for shape reconstruction. Our method combines information both from the shading of the object and from shadows cast on the scene by the object. Initially we use a method based on shadows and a method based on shading independently. The shadow based method utilizes brightness variation inside the shadows cast by the object, whereas the shading based method utilizes brightness variation on the directly illuminated portions of the object. We demonstrate how the two sources of information complement each other in a number of occasions. We then describe an approach that integrates the two methods, with results superior to those obtained if the two methods are used separately. The resulting illumination information can be used (i) to render synthetic objects in a real photograph with correct illumination effects, and (ii) to virtually re-light the scene.
Starting Page	38
Ending Page	47
File Size	1752369
Page Count	10
File Format	PDF
ISBN	0769517846
DOI	10.1109/PCCGA.2002.1167837
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2002-10-09
Publisher Place	China
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Light sources Virtual reality Layout Geometry Lighting Brightness Object detection Reflectivity Calibration Rendering (computer graphics)
Content Type	Text
Resource Type	Article

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