Newsgroups: comp.graphics
Path: utzoo!utgpu!jarvis.csri.toronto.edu!dgp.toronto.edu!elf
From: elf@dgp.toronto.edu (Eugene Fiume)
Subject: Re: raytracing in || (supersampling speedup)
Message-ID: <8811301336.AA04765@explorer.dgp.toronto.edu>
Keywords: 4 rays per pixel
Organization: University of Toronto, CSRI
References: <9700001@datacube> <3148@uoregon.uoregon.edu> <1351@umbc3.UMD.EDU> <5263@cbmvax.UUCP> <5548@thorin.cs.unc.edu> <7034@watcgl.waterloo.edu>
Date: Wed, 30 Nov 88 08:36:27 EST

In article <7034@watcgl.waterloo.edu> awpaeth@watcgl.waterloo.edu (Alan Wm Paeth) writes:
>
>The technique used by Sweeney in 1984 (while here at Waterloo) compares the four
>pixel-corner rays and if they are not in close agreement subdivides the pixel.
>The recursion terminates either when the rays from the subpixel's corners are
>in close agreement or when some max depth is reached. The subpixel values are
>averaged to form the parent pixel intensity (though a more general convolution
>could be used in gathering up the subpieces).

This technique was, of course, mentioned in Whitted's 1980 paper.
-- 
Eugene Fiume
Dynamic Graphics Project
University of Toronto
elf@dgp.utoronto (BITNET); elf@dgp.toronto.edu (CSNET/UUCP)