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_id	fafa
authors	Marr, David
year	1982
title	Vision: A Computational Investigation into the Human Representation and Processing of Visual Information
source	New York, NY: W.H. Freeman and Company
summary	Marr's demonstrations that retinal receptive field geometry could be derived by Fourier transformation of spatial frequency sensitivity data, that edges and contours could be detected by finding zero crossings in the light gradient by taking the Laplacian or second directional derivative, that excitatory and inhibitory receptive fields could be constructed from "DOG" functions (the difference of two Gaussians), and that the visual system used a two-dimensional convolution integral with a Gaussian prefilter as an operator for bandwidth optimation on the retinal light distribution, were more powerful than anything that had been seen up to that time. It was as if vision research suddenly acquired its own Principia Mathematica, or perhaps General Relativity Theory, in terms of the new explanatory power Marr's theories provided. Truly an extraordinary book from an extraordinary thinker in the area of perception, vision, and the brain.
series	other
last changed	2003/04/23 15:14

_id	e1d1
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
last changed	2003/06/02 13:58

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