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1992-09-13
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From nucsrl!casbah.acns.nwu.edu!raven.alaska.edu!bionet!ucselx!sol.ctr.columbia.edu!spool.mu.edu!mips!dimacs.rutgers.edu!dorm.rutgers.edu!uupsi!eye!erich Tue Jul 16 21:36:32 CDT 1991
Article: 2971 of comp.graphics
Path: nucsrl!casbah.acns.nwu.edu!raven.alaska.edu!bionet!ucselx!sol.ctr.columbia.edu!spool.mu.edu!mips!dimacs.rutgers.edu!dorm.rutgers.edu!uupsi!eye!erich
From: erich@eye.com (Eric Haines)
Newsgroups: comp.graphics
Subject: Ray Tracing News, Volume 4, Number 2 (pretty darn long)
Keywords: ray tracing
Message-ID: <1991Jul15.144908.8079@eye.com>
Date: 15 Jul 91 14:49:08 GMT
Sender: Eric Haines
Reply-To: erich@eye.com (Eric Haines)
Organization: "3D/Eye Inc., Ithaca, NY"
Lines: 1165
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"Light Makes Right"
July 15, 1991
Volume 4, Number 2
Compiled by Eric Haines, 3D/Eye Inc, 2359 Triphammer Rd, Ithaca, NY 14850
erich@eye.com or uupsi!eye!erich
Archive locations: anonymous FTP at weedeater.math.yale.edu [130.132.23.17],
/pub/RTNews, and others.
UUCP archive access: write Kory Hamzeh (quad.com!avatar!kory) for info.
Contents:
Introduction - SIGGRAPH get-together, etc
New People, Address Changes, etc
Ray Tracing Related FTP sites, compiled by Eric Haines
Ray Tracing, the way I do it, by Haakan 'Zap' Andersson
More Thoughts on Anti-Aliasing, by John Woolverton
Spatial Measures for Accelerated Ray Tracing, by John Spackman
Barcelona Workshop Summary, by Arjan Kok
Book Announcement, from Stuart Green
Spiral Scene Generator, by Tom Wilson
An Announcement From The 'Paper Bank' Project, by Juhana Kouhia
Proceedings of Graphics Interface '91 Availability, by Irene Gargantini
NFF Previewers, by Bernie Kirby, Patrick Flynn, Mike Gigante, Eric Haines
RayTracker Demos Available, by Jari Kahkonen
RayTracker Info, by Zap Andersson
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Introduction
I admit it, I've strayed from the One True Way of pure ray tracing: I've
been dabbling in radiosity. We recently finished a film of Ronchamp chapel
illuminated with radiosity techniques, rendered with an a-buffer, and with
stochastic ray traced beams of lights streaming in the windows, coming to a
film show near you (SIGGRAPH and Eurographics, I hope). My one piece of
advice from doing the film is this: try to make everything originate from
you. The rights to music are amazingly expensive (in our case, thousands of
dollars for just one showing at SIGGRAPH), and tracking down and obtaining
permission to use quotes, drawings, or photos can be a real hassle.
If you want to know how we did the beams of light effect, get the
"Frontiers in Rendering" course notes (or even go to the course). There
should be some good & weird topics at this course, such as Charlie Gunn's
animations of hyperbolic space (where dodecahedra meet 8 at a corner) and
Peter Kochevar's shading computations via cellular automata ("the lunatic
fringe of rendering", as he puts it). Me, I'm going to talk about ray
casting for radiosity, and also all the things that drive me crazy about
radiosity (with lots of dirty laundry pictures showing where and how radiosity
falls apart, and some solutions).
As usual, there will be a ray tracing researchers get-together at SIGGRAPH,
open to anyone. On Thursday from 5:15 to 6:30 at room N223 in the convention
center we'll meet and gab about this and that. No planned activities, just a
place and time to connect names to faces.
When our son Ryan was born, Zap Andersson sent a nice little GIF from his
ray tracer of a cigar in an ashtray as congratulations; the texture mapped
smoke was particularly well done. Zap was just married, so I was able to send
two interlinked rings with his wife's & his names inscribed in them.
Definitely a future trend: graphical greeting cards/presents by e-mail.
The wedding rings picture was also my first worthwhile test image using
the two-pass software we've developed to blend radiosity and ray-tracing. The
nice thing about two-pass algorithms is that you generally get soft shadows
cheaply, as the radiosity mesh picks up the shadows adaptively and so saves
the ray tracer much shadow-testing time. You also get all the nice features
of ray tracing, including exact geometry: spheres are truly spherical,
instead of straight radiosity's polygonalized representation. Being able to
combine the sampling mesh from radiosity and the geometry from ray tracing is
usually a great combination.
Just so it is not buried in the bits: note that Greg Ward's Radiance ray
tracer with radiosity effects built in (see his SIGGRAPH paper) is now
available via FTP. As important, he has also begun a directory of "test"
radiosity scenes which researchers can use to attempt to compare radiosities
generated for these scenes. For those of you trying to write your own
radiosity system this is a valuable tool for checking if you're getting
anything near the right answer. Finally, Greg has also collected various
object models and made them available.
Books of note: _Digital Image Warping_ by George Wolberg (IEEE Computer
Society Press Monograph, 1990) is very handy if you're involved in texture
mapping. Many different topics are covered, with good illustrations and
sample code. It's not the ultimate book from a theory standpoint, but is very
practical and understandable. Recommended.
Last issue someone mentioned the book _Fractal Programming and Ray Tracing
with C++_ by Roger Stevens (M&T Books for $30, $20 more for the disk of code).
I bought it, and cannot recommend it to the general reader. If you are
getting your feet wet with C++ it might be of some interest, and beginning PC
programmers might find bits of it useful. The author takes Steve Koren's QRT
input language and develops a C++ ray tracer for it. One major problem with
such a ray tracer is that there is no definition for a general polygon; only
triangles and parallelograms are provided. There's a lot of padding in the
book, with 20 or 30 page stretches of nothing but code listings, and 70 pages
of data file listings (42 pages for his version of "sphereflake" alone - he
could have printed the listings for the whole SPD package in that space!).
The index is somewhat dysfunctional, e.g. minor variations on the words
"bounding boxes" are given separate listings, some with wrong page numbers.
References to almost all other work in ray tracing is missing, and the
interested reader is given almost no help on where to go for more information.
I wish it had been better.
Coming out at SIGGRAPH is "Graphics Gems II", edited by Jim Arvo this time
around. Does anyone else know of good books to look for there? The other
SIGGRAPH question: any guesses on how many times humorous references to
"Monte Carlo" techniques will be made?
Get a job: one subscriber pointed out an interesting relationship between
public domain ray tracers and future employment. The authors of two of the
more popular public domain ray tracers (MTV by Mark VandeWettering and
RayShade by Craig Kolb) are currently employed by PIXAR. Now if David Buck of
DKBtrace gets a job there (no, I have no idea if he's even looking for work)
this relationship can become a firmly established principle...
Finally: I've pretty much stopped culling USENET for news in
comp.graphics, figuring that most everyone plows through this stuff by now.
What convinced me was looking at my file of comp.graphics clippings and seeing
that the accumulation surpassed half a megabyte! Updating the ray tracing and
radiosity bibliographies, mailing list, and the FTP site list are time
consuming enough; also running a clippi