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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. CMU-CS- 82-100
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 Huffman-Clowes line labels to
series CADline
references Content-type: text/plain
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