authors 
Shafer, Steven A. and Kanade, Takeo 
year 
1982 
title 
Using Shadows in Finding Surface Orientations 
source 
61 p. : ill.` Pittsburgh, PA: Department of Computer Science, CMU, January, 1982. CMUCS 82100 
summary 
Given a line drawing from an image with shadow regions identified, the shapes of the shadows can be used to generate constraints on the orientations of the surfaces involved. This paper describes the theory which governs those constraints under orthography. A 'Basic Shadow Problem' is first posed, in which there is a single light source, and a single surface casts a shadow on another (background) surface. There are six parameters to determine: the orientation (2 parameters) for each surface, and the direction of the vector (2 parameters) pointing at the light source. If some set of 3 of these are given in advance, the remaining 3 can then be determined geometrically 
keywords 
The solution method consists of identifying 'illumination surfaces' consisting of illumination vectors, assigning HuffmanClowes line labels to 
series 
CADline 
references 
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last changed 
2003/06/02 11:58 
