Path: utzoo!utgpu!watmath!clyde!att!pacbell!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!encore!cloud9!cme From: cme@cloud9.UUCP (Carl Ellison) Newsgroups: comp.graphics Subject: Re: raytracing in || Summary: TANSTAAFL Keywords: 4 rays per pixel ???? Message-ID: <2595@cloud9.UUCP> Date: 29 Nov 88 17:41:47 GMT References: <9700001@datacube> <3148@uoregon.uoregon.edu> <1351@umbc3.UMD.EDU> <5548@thorin.cs.unc.edu> Organization: Stratus Computer, Inc., Marlboro, MA Lines: 23 In article <5548@thorin.cs.unc.edu>, brown@tyler.cs.unc.edu (Lurch) writes: > > From what I understand, the way to achieve 4 rays per pixel is to sample at > vertical resolution +1, horizontal resolution +1, and treat each ray as a > 'corner' of each pixel, and average those values. This is super cheap compared > to sampling at twice vertical and horizontal. > There ain't no such thing as a free lunch. The re-use of corners for all pixels which share them turns this into filtering AFTER sampling -- and sampling only at pixel resolution. All the aliasing which a 1-sample per pixel image would have is carefully preserved this way -- only the final picture (both good stuff and aliasing) is blurred. Have a nice day, --Carl Ellison ...!harvard!anvil!es!cme (normal mail address) ...!ulowell!cloud9!cme (usenet news reading) (standard disclaimer)