peter@sugar.UUCP (Peter da Silva) (07/29/87)
OK, I think I have come up with something the rendering equation won't cover. Chromatic abberation. You know... the stuff that makes rainbows colorful and diamonds sparkly. I don't think backtracking would give you that. Preprocessing and painting will. Hold on. I think I can see how backtracking could work. You just calculate a sample of paths whenever you refract. Tag each path with a color value. Except for small angles the spread will probably be too small to bother with. Anyway, when you recombine the paths you selectively reduce the contribution of the other colors. I'm not a computer graphics heavy, and I haven't reda the article, but I don't remember seeing this one described anywhere. Does this get me a citation :->? -- -- Peter da Silva `-_-' ...!seismo!soma!uhnix1!sugar!peter (I said, NO PHOTOS!)
jon@oddhack.caltech.edu (Jon Leech) (08/02/87)
Summary: Expires: Sender: Followup-To: Distribution: In article <439@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes: >OK, I think I have come up with something the rendering equation won't >cover. Chromatic abberation. You know... the stuff that makes rainbows >colorful and diamonds sparkly. I don't think backtracking would give >you that. Preprocessing and painting will. Make sure you distinguish the rendering equation and various SOLUTIONS to the rendering equation. I think many people treat these two aspects of Kajiya's paper as the same thing. If you want wavelength-dependent effects, tracing rays of different wavelengths seems the logical way to go. -- Jon Leech (jon@csvax.caltech.edu || ...seismo!cit-vax!jon) Caltech Computer Science Graphics Group __@/ Down with Mars! Back to the Moon first.
spencer@osu-cgrg.UUCP (Steve Spencer) (08/02/87)
In article <439@sugar.UUCP>, peter@sugar.UUCP (Peter da Silva) writes: > OK, I think I have come up with something the rendering equation won't > cover. Chromatic abberation. You know... the stuff that makes rainbows > colorful and diamonds sparkly. I think there was an article about choiastisy (sp?) (the article dealt with glass spheres and marbles...) in _The Visual Computer_ sometime last year. (Spring 1986??) Is this what you're thinking of? -- ...I'm growing older but not up... - Jimmy Buffett Stephen Spencer, Graduate Student The Computer Graphics Research Group The Ohio State University 1501 Neil Avenue, Columbus OH 43210 {decvax,ucbvax}!cbosg!osu-cgrg!spencer (uucp)
ksbooth@watcgl.UUCP (08/05/87)
Rainbows require only that the ray-tracing take into account the frequency of the light when refractions are computed. This has been done. The rendering equation can presumably include this (as can the other popular techniques). The only interesting question is how to do this efficiently. People have been and are working on this too.
skinner@saturn.ucsc.edu (Robert Skinner) (08/08/87)
In article <439@sugar.UUCP>, peter@sugar.UUCP (Peter da Silva) writes: > OK, I think I have come up with something the rendering equation won't > cover. Chromatic abberation. You know... the stuff that makes rainbows > colorful and diamonds sparkly. > > I don't remember seeing this one described anywhere. Does this get me > a citation :->? Rainbows were done by Ken Musgrave here at UCSC this past spring. He basicly extended the distributed ray tracing concept to include sampling the frequency of light. Rays were tagged with a frequency when they hit a refracting object, and the resulting illumination values were filtered by the color of the given frequency. This works for prisms and diamonds, etc. The rainbow position is easily caluculated by a dot-product and table look-up. This does not handle rainbows cast on a wall from a prism... That is really a multicolored caustic.... .... and the caustic debate continues ... ---------------- Robert Skinner skinner@saturn.ucsc.edu@csnet-relay
kent@xanth.UUCP (Kent Paul Dolan) (08/10/87)
In article <583@saturn.ucsc.edu> skinner@saturn.ucsc.edu (Robert Skinner) writes: > >This does not handle rainbows cast on a wall from a prism... >That is really a multicolored caustic.... >.... and the caustic debate continues ... >Robert Skinner >skinner@saturn.ucsc.edu@csnet-relay No question, this is the only newsgroup where a caustic debate can go on and no one gets their feelings hurt. ;-) Kent, the man from xanth.