Graphics Plus/Graphics Plus.iso/info/rtnews/rtnv7n5

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            "Light Makes Right"

             October 13, 1994
            Volume 7, Number 5

Compiled by Eric Haines, 3D/Eye Inc, 1050 Craft Road, Ithaca, NY 14850
    [e-mail]
All contents are copyright (c) 1994 by the individual authors,
    all rights reserved
Archive locations:  anonymous FTP at princeton.edu (128.112.128.1)
    /pub/Graphics/RTNews, wuarchive.wustl.edu:/graphics/graphics/RTNews,
    and many others.

Contents:
    Introduction
    New People
    Ray Tracing Roundup
    Recent Ray Tracing Papers
    Rumor Mill
    AERO Animation/Simulation System version 1.5.1, by Thomas Braeunl
    A Brief Review of [an old] AERO, by Dave Negro
    Photon Tracing, by Chris Thornborrow and Greg Ward
    Faster Than POV-RAY 2.1, by Dieter Bayer
    Z Buffer Based Rendering Program, by Raghu Karinthi
    Gossamer, a Free Macintosh VR/3D Renderer, by Jon Blossom
    Antialiasing Issues, by Arijan Siska
    Microcosm, by Abe Megahed of Cosmic Software
    Fisheye Lens Distortion, by Greg Ward
    Optical Ray Tracers
    Correcting Normal Direction, by Gavin Bell
    Graphics Gems IV Table of Contents, by Paul Heckbert
    Beyond Graphics Gems, by Paul Heckbert
    Radiosity vs. Ray Tracing, by Rico Tsang
    ACM SIGGRAPH Online Bibliography Updated, by Frank Kappe
    How to be Notified of New POV Releases
    PoVSB Windows-based Modeler v0.85, by Jeff Hauswirth
    Porting Rayshade, PBM, etc from Unix to DOS, by Mike Castle
    REYES & Patents, William C. Archibald
    Going from AutoCAD and 3DS into Ray Tracing, by Sean Ross
    Computer Lego Modeling, by Paul Gyugyi
    Rowe's Ray Tracing World BBS, by Harry Rowe
    On Using BSP trees, by Benton Jackson
    Books about Commercial Renderers, by Don Lewis, Jimbo and Yury German

-------------------------------------------------------------------------------

Introduction

    Another SIGGRAPH has come and gone, and it was a pretty fun one.
Getting soaked time and again along with other allegedly intelligent people by
the whales at the SeaWorld reception was definitely memorable.  In many ways
this conference was better than previous years.  The proceedings and course
notes were also provided on CD-ROM (some headaches on some machines, but
that's the norm).  Being able to move course to course was wonderful (even
with the headache of getting to and from Stouffer's, which was no fault of the
conference organizers).  The addition of the technical sketches sessions and
parallel paper sessions were both plusses to me.  Note that there are a number
of great resources on the various CD-ROMs, e.g. the latest release of
Radiance (since there was a paper on the system in the proceedings this year).

    The most noticeable technology for me was Apple's QuickTime VR.
Nothing earth-shattering, but something which looks to be popular.
Essentially you can move from view to view of an environment.  You have a
panoramic view of wherever you're located, so you can turn your head, zoom in
on something, and even look up and down a bit:  there's a nice illusion that
you're interacting with the environment but without having more than a single
panoramic view for a location.  The software does all the distortion
correction on the fly.  The first product that is out using this technique is
a tour of the Enterprise (TNG) on CD-ROM, and I suspect you'll see a lot of
Apple's technique in upcoming CD-ROM tours and adventure games (e.g. rumor
has it the Myst guys were looking at the technique).

    So what's this have to do with ray tracing?  Well, ray tracing is a
natural for rendering panoramic views (Ken Musgrave has a Gem on how to do
this in "Graphics Gems III").  Scanline images can be used and glued together
and then warped, but ray traced images give you the distortion you need for
free and at the sampling rates you need where you need them.

    This is yet another catch-up issue, where the bits and pieces left in
the queue since April are gathered up and spewed out now.  If anything, have
the material molder in my files for a few months meant I've culled a bit more
than usual, leaving a denser filling with a firm yet flakey crust.  Food
imagery aside, there *are* some worthwhile bits in this issue:  AERO, a demo
of Microcosm, a new z-buffer renderer, and so on.  Next issue will have more
juicy stuff (and I really do hope to get it out before the Millenium arrives),
including an announcement of a non-Pixar-produced shareware RenderMan
implementation!

-------------------------------------------------------------------------------

New People

# Werner Purgathofer - radiosity, ray tracing, visualization, color
# Technical University of Vienna
# Institute of Computer Graphics
# Karlsplatz 13 / 186-2
# A-1040 Wien / Austria
# [phone]
alias [e-mail]

I am a professor of computer graphics, my main job consisting of teaching,
administration and research.  My group consists of about 12 people, including
a technician and a secretary.  We did a lot of ray tracing some years ago,
including distributed ray tracing (see e.g. Eurographics 86), now we are
concentrating on radiosity issues.  As (forward) ray tracing becomes more and
more important here, we are almost back where we started!

-------------------------------------------------------------------------------

Ray Tracing Roundup


Thought folks might be interested in the On-Line Ray-Tracing Bibliography,
available over the World Wide Web via URL:

    http://www.cm.cf.ac.uk/Ray.Tracing/

Even those without Web clients like Mosaic can check this out by telneting to
one of these sites:

    If you're near:         Telnet to:

    Switzerland:            info.cern.ch or 128.141.201.74
    Kansas, USA:            ukanaix.cc.ukans.edu  (login as www)
    New Jersey, USA:        www.njit.edu  (login as www)
    Israel:                 vms.huji.ac.il or 128.139.4.3 (login as www)
    Slovakia:               sun.uakom.cs (slow link; use only from nearby)
    Hungary:                fserv.kfki.hu (slow link, login as www)
    Finland:                info.funet.fi or 128.214.6.100

Mark Maimone ([e-mail])

[This is Ian Grimstead's doing, and "bibliography" is a misnomer - it's a
great place to start looking for all sorts of ray tracing and rendering
resources, with links to just about everywhere.  Really, I could just list
this site each issue and not have to list most of the other resources that I
do.  -EAH]

--------

The FAQ for comp.graphics.algorithms are available at:

http://www.cis.ohio-state/hypertext/faq/usenet/graphics/algorithms-faq/faq.html
ftp://rtfm.mit.edu/pub/usenet-by-group/news.answers/graphics/algorithms-faq

Also available at:
ftp://wuarchive.wustl.edu/graphics/graphics/mail-lists/comp.graphics.algorithms

FYI, all usenet FAQ's are available with Mosaic via:
http://www.cis.ohio-state/hypertext/faq/usenet/top.html

Jon Stone ([e-mail])

--------

A computer graphics related FTP list [maintained by Nick Fotis and myself.
-EAH] is kept at:

wuarchive.wustl.edu: /graphics/graphics/ray/GraphicsFTP.txt

George Kyriazis ([e-mail])

--------

I've been playing around with HTML and the World-Wide Web lately, and I have
created hypertext versions of the three latest RTNews issues, with more to
come when I get the time and energy to do it...

RTNews is at
    http://www.lysator.liu.se:7500/users/ture/rtnews.html

I also have some general graphics stuff att .../graphics.html, and my own
presentation at .../ture.html

Ture P\aa{}lsson ([e-mail])

--------

Texture Collections

:       I'm looking into different texture collections on CD-ROMs.  Are
:       there any that are absolutely awesome, or others that should be
:       avoided (i.e. not worth the money)?  "Accents" looks pretty nice
:       (in reviews, etc), and also Pixar's $99 offer for "One Twenty Eight"
:       CD-ROM texture collection looks good.

I just finished writing an article on this very topic for Digital Video
Magazine.  It should be in the September issue, and it covers about twenty or
so packages for the Amiga, Mac and PC, most of them on CD-ROM.  The Pixar set
you mentioned is very good, as are Autodesk's Texture Universe and Texture
City.  Check the article out for more info on a bunch of packages.  Hope this
is helpful.

[Digital Video Magazine is at 603-924-0100 in Peterborough, NH. -EAH]

Dave Thomas ([e-mail])
Moving Pixels
(Client, looking at image of a sphere on a monitor: "Can we make it rounder?")

--------

Recent Uploads to ftp.cica.indiana.edu

File: desktop/gcad110.zip                                Date:  940311
Desc: GammaCAD v1.10 <ASP> - Full featured

File: programr/3dlib30a.zip                              Date:  940315
File: programr/3dlib30b.zip                              Date:  940315
Desc: C++ & Pascal 3D graphic animation

--------

As a new feature, the fractal FAQ has some links for use with the World Wide
Web.  It can be accessed with a program such as xmosaic at
  http://www.cis.ohio-state.edu/hypertext/faq/usenet/fractal-faq/faq.html

Ken Shirriff ([e-mail])

--------

New version of RTrace 8.4.0

There is a new version of the RTrace ray-tracing package (8.4.0) at
asterix.inescn.pt [192.35.246.17] in directory pub/RTrace.  Check the README
file.

Antonio Costa, Comp. Graphics/CAD ([e-mail])

--------

New Game Programming FTP-Place

I have the great pleasure to officially announce the new (pc) game programming
oriented ftp-place teeri.oulu.fi.  It's currently an old sun3, has max 20
user limit, is located in Finland (Europe) and has about 40M more or less game
programming oriented material online + lots more to come.

    teeri.oulu.fi:/pub/msdos/programming
    (uploads to teeri.oulu.fi:/incoming with a .txt file, please)

There are graphics libs, sound libs, hardware tech specs, file format specs,
drawing utils, music composing utils, sample game source, some carefully
selected FAQs, file format converters, all 3 known Game Programmers Magazines,
is the official home && dist site for Game Programmers Encyclopedia etc.  etc.

The PC Games Programmers Encyclopedia 1.0 (PC-GPE) is in
/pub/msdos/programming/gpe/pcgpe10.zip

Jouni Miettunen ([e-mail])

[Another place to look for PC related graphics source code is:
ftp.uwp.edu: /pub/msdos/demos/programming/source  -EAH]

--------

PCFormat (UK) RTPics on cover CD

Just thought UK readers might like to know that this month, PC Format magazine
have launched a copy which comes with a CD rather than the usual disks.  On it
are over 150 ray-traced images, most of which are pretty stunning and in at
least 640x480 (GIFs though :-(, so only 256 colours).  The ray-traced trees
generated with LParser are particularly gobsmacking!  Even 'Frosty' is on
there, but compared to the rest, I found it to be pretty average (sorry Dan,
but I think some of your others are MUCH better).

IMHO, it's well worth a look, and Pc Format can be reached at
[e-mail] if you want to try & persuade them to put more
ray-tracing stuff on the disc in future (such as source files, image data
etc).

PS:  The Bowling.GIF has incredible motion blur (dunno what it was done on
though!)

William Turner ([e-mail])

--------

Geombib Reminder

Otfried Schwarzkopf has set up an experimental server on the world-wide web
for the geometry biblio; you can try it by pointing your browser (e.g.  mosaic
for xwindows) at

    http://www.cs.ruu.nl/people/otfried/html/geombib.html

The server can be used to do remote searches on the bibliography (it has
biblook under the hood).  When the entry has been annotated with the new URL
field, the server will recognize this and allow you to download the network
object pointed to, e.g.  a Postscript copy of a techreport.  (You can find
some examples by looking for "ftp" in "any" field.)  If you have comments or
suggestions regarding the server, please send them to [e-mail].

If you wish to join the computational geometry mailing list, send email with
body of "subscribe geombib" to [e-mail].  Beware that mail sent
to [e-mail] gets a form letter from majordomo but not a
subscription.

[You can FTP the bib from cs.usask.ca: /pub/geometry/geombib.tar.Z  -EAH]

Bill Jones ([e-mail])

--------

Animation FTP Site

toe.cs.berkeley.edu in directory /pub/multimedia/mpeg/movies

has some quite good mpeg streams including the morphing sequence from Michael
Jackson's 'Black and white' video.

Jim Marsden ([e-mail])

--------

I have recently completed version 1.1 of RenderCAD-PRO, a modeling and
ray-tracing application for the Macintosh.  Its easy graphic user interface
can be used to generate photo-realistic single images and multi-image
animations.  A free demo (requires Mac w/ FPU co-pro) of this $45 package is
available.  Please send info requests to...

Paul Rybarczyk ([e-mail])

--------

If you have direct Internet access, you can learn about BRL-CAD via:

ftp to ftp.arl.mil, directory /brl-cad

Mosaic/WWW to the following URL:
    http://www.brl.mil/software/brlcad/index.html

Lee A. Butler ([e-mail])

--------

The current version of the Stereogram FAQ is in the HTML file at
    http://www.cs.waikato.ac.nz/~singlis/sirds.html
or can be FTPed from:
    katz.anu.edu.au [150.203.7.91] :  /pub/stereograms
(which also has a lot of other SIRDS related information)

[Stereograms are those things you see in the mall (trade name "Hollusion")
that you try to stare at and defocus and see the dinosaur or whatever in 3D.
I could never see the effect until I learned about the techniques listed in the
FAQ.  Fun illusion, and it turns out to be very easy to implement as a post
process to a ray tracer - I believe people have already done it for POV and
Rayshade.  Also, at the listed FTP site there is a ray tracer called raysis
which is devoted to this task.  To do this stuff yourself you can try to
decode the FAQ (it's a tad cryptic when it comes to actually saying what to do
for SIS), buy the new book _Create Stereograms on Your PC_ by Dan Richardson,
Waite Group Press, or wait an issue:  I hope to write up the 20-30 lines of
code I used to add it to my renderer for the heck of it.  -EAH]

--------

Raytech is a BBS specialising in ray tracing.  It is located in northern
Scotland, and their telephone number is 44-862-832020.

Adam Fulcher ([e-mail])

--------

Just about everything that always gets asked over and over again on
rec.games.programmer is covered in the latest Dr. Dobbs:  circle, ellipse,
line, texture mapping, landscape generation, and even ray-tracing.  So before
you ask get that episode (#216 July 1994 ddj).

Ben ([e-mail])

--------

RT Ray Tracer

I have implemented a CSG Ray Tracer with lots of primitives, textures,
bounding volumes in C (but I've no multi-processing/wire-frame stuff).

My Ray Tracer is called RT and is available on
ftp-os2.nmsu.edu:os2/2_x/graphics/rt.zip.  It comes with full portable C
source and uses the GBM module for file I/O (found in same directory as
gbmsrc.zip).  I will refresh it with a version less sensitive to rounding
errors sometime soon.

Andy Key ([e-mail])

--------

Equation for a Cow, er Frog

There are some datasets at:

    http://george.lbl.gov/ITG.html

including a rasterization of a frog that was made by freezing, slicing, and
scanning.  (They planned to do an MRI scan, but frogs don't scan well.)

There's also MRI data for an orange, a tomato, a pumpkin, and a rat.

Roger Critchlow ([e-mail])

--------

The WorldToolKit User's Group (SIG-WTK) electronic archive is located at

    artemis.arc.nasa.gov: /sig-wtk

This anonymous ftp site serves as the software and documents library for the
SIG-WTK.  It is intended to serve the needs of active WTK users and other
parties interested in WorldToolKit.

The site is organized within the ~ftp/sig-wtk as follows:

        incoming/       for anonymous contributions
        models/         3D objects in various formats (NFF, DXF, etc.)
        textures/       textures in various formats (SGI, Targa, etc.)

[Note that the NFF format referred to is Sense8's NFF format, not mine. -EAH]

Terry Fong ([e-mail])

--------

Wavefront site:

    http://wavefront.wti.com

(WWW only?)

Kevin Bjorke ([e-mail])

--------

The author of TextureSynth (Joshua Jeffe) has written a new texture
generating application called TextureScape, which uses postscript shapes as
the basis of really cool, resolution-independent textures. It can also be used
to create animated textures for use in multimedia.  TextureSynth is
published by Specular International (call 1-800-433-SPEC for more info).

Peter E. Lee ([e-mail])

--------

3D Studio utils uploaded to Avalon

I have uploaded 3D Studio IPAS routines and utilities to
avalon.chinalake.navy.mil (129.131.1.225) /pub/utils/3ds/

Each file is accompanied by a .txt file.  I didn't write, haven't used, don't
know anything else about these utilities.  Just passing them on.

If you have any problems connecting to avalon, try its mirror site:
    Kubota Pacific, ftp.kpc.com (144.52.120.9) /pub/mirror/avalon

Pat Kane ([e-mail])

--------

Also at avalon.chinalake.navy.mil, in the pub/misc directory, are all sorts
of interesting PC software, including the fabled TrueSpace Caligari demo
version (doesn't save/restore; ts_demo.zip), a Real3D demo (which is supposed
to be tough to use without the documentation), and other interesting things.

--------

Acoustic Simulation

Renkus-Heinz, a speaker manufacturer from California, distributes EASE
(Electro Acoustic Simulation for Engineers), and EASE Jr.  Both run on MS-Dos
systems.  Ease also supports aurilization using a companion program called
EARS and a DSP board.  Ease allows you to calculate reverb time, impulse
response, frequency response of systems, ray tracing, and perform sound system
design.  Ease Jr allows reverb time and sound system design calculations.
Both programs allow wireframe room models to be built in the program, or
importation of 3-D DXF files.

Jay Paul ([e-mail])

[it had the magic words "ray tracing" in there, so I included it. -EAH]

--------

Blob Sculptor Update

We have released Blob Sculptor for Windows 1.0.  It has the same functionality
as the DOS version.  Ron Praver ported the DOS version to Windoze.  [look
around on ftp.povray.org, I think it's in there somewhere. -EAH]

Blob Sculptor, ver 2.0 for _DOS_ is almost ready to be released.  The new
functionality includes:

        * better user interface
        * camera can be interactively located
        * support for multiple blobs, i.e. components within a blob interact
          with each other but blobs don't interact with each other
        * sphere, cones and cylinder shaped components
        * faster preview mode

Version 2.0 has been beta tested for some time and already has produced some
awesome images.  For example, Edgar L. Ibarra has produced various images
including cartoon-like characters:  dog, candle holder (a la Beauty and the
Beast), and a baby.  You can find these at CompuServe's GraphDev forum.  He
renders the objects with Imagine 3.0.

I've been working on a spline blob component.  The component consists of 3
points which are created in 3D space.  A spline is used to interpolate them
and a radius is defined to give the object a bent cylinder look.  The
component also permits the modification of a tension parameter which gives the
user more versatility without the need to use more points.  Uses for this, you
ask?  well, if you want to create the fingers in a hand you don't need to use
spheres or 2 or more cylinders to do the job...just 1 spline blob will do the
job.  Think of a spline blob as a generalized cylinder or playdough in the
shape of a cylinder which can be bent.

Alfonso Hermida ([e-mail])

--------

Radiance Related
================

SIGGRAPH Proceedings Distribution

Other than a paper about the Radiance system in the SIGGRAPH '94 Proceedings,
the entire Radiance system is included on the Proceedings CD ROM.  It's in
/papers/ward/rad2r4.tz (uncompress and read .tar, I assume).

Eric Haines

----

Radiance vs. POV

I have found Radiance to be comparable in speed to POV.  Once the octree is
generated the tracing times are even shorter than POV.  It has very efficient
pruning and the tracing times go up less than linearly with the increase in
the number of polygons in a scene.  And besides - the results are MUCH better
in terms of realistic-looking lighting and better-looking surfaces.  In my
opinion Radiance is the best ray-tracing package on any platform - I use it on
an Amiga.  The main problem with Radiance is lack of a good modeler and the
many other support programs that are available for POV.

Alison Colman ([e-mail])

--------

POV Related
===========

Andy Wardley ([e-mail]) notes:

I've just uploaded geodome1.zip to uniwa which is the utility for creating the
geodome data models.

Non-PC users will be glad to hear that it *does* include source.

--

Harry Rowe ([e-mail]) comments:

Like others, I would just like to say GREAT scene!  The sky is one of the best
I've seen.  I scarfed the GIF and your utility from uniwa and placed it on my
BBS (Rowe's Ray Tracing World BBS [phone]).  It will be on my custom
600 meg Ray Tracing/Graphics CD coming this fall

----

The POV-Utilities 2.0 for the Mac have hit the streets.  The package is now
available on CompuServe, Go GRAPHDEV, Lib 8, POVUTL.SIT.  It is also available
via anonymous ftp on the internet, from the Australian secondary official
POV-Ray site, ftp.uwa.edu.au (and ftp.povray.org for N.American users, I
assume), under pub/povray/utilities/.  As always, feedback and bug reports are
encouraged.

Also look for my shareware System 7 "MooVer" utility, that converts a series
of (POV-Ray animated?)  PICT files into a QuickTime movie with a simple
drag-n-drop.  It should also be showing up on uniwa, and is on
CIS/GRAPHDEV/Lib 6/MOOVER.SIT.

Eduard Schwan ([e-mail])

----

New Povray Clipart Available

I've uploaded Povray V2.0 files to avalon.chinalake.navy.mil.  They can be
found at pub/objects/pov.  They were all converted from *.obj files found on
avalon.chinalake.navy.mil in pub/objects/obj.

Keith D. Rule ([e-mail])

[many are the free Viewpoint models, plus a few Star Trek thingies. -EAH]

----

POV Utility Information on the WWW

I have just set up a WWW page for POV utilities, containing information about
a few popular ones, and also allowing you to download them directly from the
page.  For most people that should be faster than the various ftp sites, as
well as having the advantage that you actually get some info on what the
utility is about.

The URL is http://www.ifi.uio.no/~mariusw/pov/utilities.html

Please give me feedback and point me to utilities you think should be on the
pages.

Marius Ibenhardt Watz ([e-mail])

----

Some utilities of note:  MORAY (1.5 of course !), SUDS, CTDS, POVCAD, TGA2GIF,
TTG, DXF2POV and RAYLATHE, just to mention a few.

[from the POV newsletter]

----

Faces for POV (Frosty):

    There was a thread a while back about Dan Farmer's Frosty picture and
how we wanted the .POV file.  I think in fact most people wanted the face
data, and on someone's advice on this group I got hold of the face1.3ds,
face2.3ds and face3.3ds files from avalon.chinalake.navy.mil and converted
them into .pov form with a utility also on that ftp server.  The utility for
conversion is something like 3dspov18.zip [source for conversion from 3DS is
included.  -EAH]

    The results are good, although they come out as 230-320k files that
might fill up too much space, and take a while to parse.  The face are more
like masks than real faces, but do the job so long as expressions aren't
needed.

Mr. Jonathan H. S. Peterson ([e-mail])

----

Parallel POV-Ray using PVM

I have written such a thing (somehow). It works like this:

A server is started, that takes all parameters and stuff.  The server divides
the final picture in several stripes.  The server spawns some children, that
each calculate one stripe (10 pixels high).  For this, each child starts
povray with +SL and +EL and writes the result to a file.  This file is passed
back to the server.  The server collects all files.

After all stripes have been calculated (a list of calculated stripes is
maintained, so you can abort and restart the process), all stripes are
collected into a final picture.

The results are impressive. texture1.pov-demo is rendered in 1-2 minutes
at 1280x1024 pixels.

Aaron Digulla ([sorry, no address])

--------

Rayshade Related
================

Craig Kolb has moved to Stanford, following his advisor Pat Hanrahan, and so
has pretty much bowed out of maintaining Rayshade.  In his place others are
attempting to glue together all the additions and bug fixes over the years and
get out a Rayshade 4.1.  More news as it happens.  Other than this effort,
there has been an explosion of WWW stuff for Rayshade.

----

Scattered notes from Craig Kolb:

There's an experimental version of a rayshade homepage available on the Web:

    http://www.cs.princeton.edu/grad/cek/rayshade

Thanks to Jelle van Zeijl and Stuart Warmink for providing documents, images,
and encouragement to set this up.

As some of you might have noticed, I've reorganized and expanded the
rayshade FTP archive a bit.  If you have anything that you'd like to add
(new primitives, textures, whatever), drop me a line.

Hundreds of surface definitions for Rayshade are available in:
ftp://ftp.princeton.edu/pub/Graphics/rayshade/Contrib/Libraries/surfdefs.rh.Z

Stephen Peter's excellent notes on using rayshade are now available
via the rayshade homepage (http://www.cs.princeton.edu/grad/cek/rayshade/),
and in source form on the rayshade FTP archive as Contrib/Docs/raynotes.tar.gz.

Craig Kolb ([e-mail])

----

Z Buffer (Range Map) Extension

To get this extension, ftp vacation.venari.cs.cmu.edu (128.2.209.207), don't
chdir, and use binary mode and download zbuf.tar.  You can get documentation
updates (a patch file and a new file) in the same place: file zbuf-doc.tar.

Mark Maimone ([e-mail])

----

The RayShade docs done by Jelle are up as URL:
    http://www.msi.umn.edu/miscdocs/Rayshade/index.html

-- Matt Hughes ([e-mail])

The Rayshade users' manual can now be reach at MIT via two URLs:
   http://web.mit.edu/afs/athena/activity/c/cgs/lib/html/rayshade/index.html
and
   http://www.mit.edu:8001/activities/cgs/rayshade/index.html

-Fred, Director, MIT Computer Graphics Society
     (http://www.mit.edu:8001/activities/cgs/mitcgs.html)

----

    For what it's worth, I've included a pointer to Rayshade in the
Computer Vision Home Page:
    http://www.cs.cmu.edu:8001/afs/cs/project/cil/ftp/html/vision.html

Mark Maimone ([e-mail])

----

    I've made a sample page of the standard Rayshade images (and just a
few more :-) available to the Net.  There are several ways to get at them:

    AFS filesystem:
cd /afs/cs.cmu.edu/misc/rayshade/all_mach/omega/doc/Examples/

    WWW with icons:
http://www.cs.cmu.edu:8001/afs/cs/misc/rayshade/all_mach/omega/doc/Examples/
    rayimages.html

    WWW without icons:
http://www.cs.cmu.edu:8001/afs/cs/misc/rayshade/all_mach/omega/doc/Examples/
    rayimgtxt.html

    anonymous FTP:
ftp ftp.cs.cmu.edu
login: anonymous
passwd: email
cd /afs/cs/misc/rayshade/all_mach/omega/doc/Examples/

-------------------------------------------------------------------------------

Recent Ray Tracing Papers

[This is a list of some recent research papers related to ray tracing from some
of the lesser known conferences and journals. -EAH]

----

[This paper is interesting in that it is the first independent testing of
Arvo and Kirk's 5D space subdivision ray tracing scheme.  -EAH]

G. Simiakakis and A. Day
Five-dimensional Adaptive Subdivision for Ray Tracing
Computer Graphics Forum, volume 13, number 2
(Special Issue: Rendering), pp. 133-140, June 1994.

[George Simiakis can be reached at [e-mail]]

----

Fifth Eurographics Workshop on Rendering
13-15 June 1994
Darmstadt, Germany

RAY TRACING (Chair: Erik Jansen ([e-mail]))
    [Summaries courtesy of Erik Jansen]
    [Really this session is more for global illumination via rays.  There
    were many other global illumination papers here.  -EAH]

Adaptive Splatting for Specular to Diffuse Light Transport
    Steve Collins

For a two-pass algorithm an adaptive light pass is used that deposits the
power carried by rays as 'splats' of energy flux on the surfaces using a
Gaussian distribution kernel.  The kernel of the splat is adaptively scaled
according to the 'ray wavefront' convergence or divergence, thus resolving
sharp intensity gradients in regions of high wavefront convergence and smooth
gradients in areas of divergence.


Rayvolution, An Evolutionary Ray Tracing Algorithm
    Markus Beyer, N. Sander, Brigitta Lange

In order to increase the statistical efficiency of Monte Carlo integration of
the rendering equation, evolutionary algorithms are applied to optimize the
sample distribution.  An initial population of rays evolves towards an optimal
sample ray distribution by application of generic operators and selection
mechanisms.  As a result we achieve an implicit stratification and a better
convergence towards the actual value.


Bidirectional Estimators for Light Transport
    Eric Veach, Leonidas Guibas

Monte Carlo methods do not suffer from the artifacts and limitations that
standard radisoity methods have to address, but have another well-known
artifact: noise. A major source of noise is bright indirect light. We can
construct different light paths between the light sources and the eye
either starting from the eye or from the light sources, or starting from
both meeting halfway. The different paths leads to a partitioning of the
rays. Each partition gives us a different unbiased estimator. Combining
these estimators may lead to near-optimal variance reduction.


A New Raytracing Architecture
    Robert E. Bacon, John A. Gerth, V. Alan Norton, James Kajiya

[withdrawn, unfortunately; mentioned because it sounded interesting. -EAH]

----

Computer Graphics International '94
Royal Melbourne Institute of Technology
 Melbourne, Australia, June 27 - July 1, 1994

Rendering and Display
    Kenjiro Takai Miura
    Ray Tracing Gregory-type Patches
    W. Lamotte, K. Elens, F. van Reeth and E. Flerackers
    A Parallel Ray Tracing Algorithm Using Hierarchical Bounding Volumes

Kerry Gigante ([e-mail])

----

The Fourth Eurographics Workshop on Animation and Simulation was held
in Barcelona, Spain September 4-5, 1993.

[This workshop had many papers with interesting titles, but here's the one
with those magic words "raytracing":]

Combining computer animation and video using bluebox raytracing
  M. Zeiller
  Technical University of Vienna - Austria.

Sabine Coquillart ([e-mail])

----

Abstract from the Sharp Technical Journal, #57 Nov 1993.

The Sharp Technical Journal is a Japanese language publication which
contains English abstracts for most of the articles.


Optimization of Illumination System for LC Projector Using Newly
Developed "Reverse Ray Tracing Method"

Takashi Shibatani, Hiroshi Nakanishi, Hiroshi Hamada

A new illumination simulation technique using "Reverse ray tracing
method" has been developed as a design tool for an illumination system
of an LC projector with a microlens array.  In this method, rays are
traced from an illuminated plane to a light source in opposite direction
compared to the conventional method.  This method have an advantage that
the numbers of rays to be traced is much smaller than in the case of
conventional method for required accuracy, and it presents 2-dimensional
angular distribution of the incident rays, which affect the efficiency
of the microlens array.

An illumination system for a single-panel LC projector with microlens
array with a newly developed correction lens and an aspherical mirror is
optimized to improve brightness of a screen employing this simulation
method.

Dr. David K. Kahaner ([e-mail])

[Copies of previous reports written by Kahaner can be obtained using
anonymous FTP from host cs.arizona.edu, directory japan/kahaner.reports.]

-------------------------------------------------------------------------------

Rumor Mill

[A new feature - this is simply snippets of tantalizing information from the
net that I saw no follow-up about.  If anyone has any details about these
items, let us all know.  -EAH]

John T. Chapman ([e-mail]) notes:

By the way - there's a CD-ROM rendering/ray-tracing tutorial offered through
Tiger Software and others.  It supposedly has stuff on Ray Dream Designer,
along with other programs.  Has anyone seen this?  Is it for RDD 3.0 or
earlier?  Is it worth the money?  (There is apparently two versions - a
'sampler' at about $19 or so and the full version at about $90 or so.)

----

Vareck Bostrom ([e-mail]) says:

Didn't they have a Intel Paragon doing 1 frame/sec 1024x768 or so ray tracing
at supercomputing '93?  I didn't see it myself, but my friends that did said
it was impressive.

----

NURBS Rendering, by Henrik Wann Jensen

Jouko Vuoskoski ([e-mail]) wrote:
: 1) What is the "normal" method to do ray-tracing with
: B-splines (or NURBS)?

: 2) How can I do it fast (with less accuracy)?

: I was thinking to ray-trace with facets from the control
: polygon of the B-spline. Halving the knot intervals I could
: get more accuracy. Is this right approach?

You are right.  The easiest way and also fastest (often stated) is to created
a facet representation of the NURBS-surface and halving the knot intervals is
the way to do it.  I know there is some source-code floating around - try
archie and search for nurbs.

[I vaguely recall there being some spline surface intersection code around and
about, but does anyone have any hard info?  -EAH]

-------------------------------------------------------------------------------

AERO Animation/Simulation System version 1.5.1, by Thomas Braeunl
    ([e-mail])

AERO is an X-window based tool for simulation and visualization of rigid-body
systems.  AERO contains a 3D scene editor for designing simple blocks world
scenes.  Objects may be placed in space, linked to each other, and forces may
be exerted onto them.

In animation mode, the simulation of the scene entered is carried out in real
time (depending on scene complexity) displaying 3D wire frames.  Also, a flag
can be set to generate scene description files for each time point as input
files for a ray tracing program, producing photorealistic output.

In both modes, wire frame and ray tracing scenes, the generation of stereo
images is possible.  In the case of real time wire frames a red-green
representation of the scene is rendered, which can be viewed with red-green
glasses.  For the ray tracing output, a binocular pair of scene descriptions
is generated for each time step.

AERO can be used for exploring the physical laws of mechanics and also for
generating realistic computer animations.  AERO is available free of charge as
public domain software.  Software and documentation can be copied via
"anonymous ftp" over the Internet.

The address of our server is:
    ftp.informatik.uni-stuttgart.de  (currently 129.69.211.2)
The directory is:
    pub/AERO

[Note that AERO 1.5.1 now outputs POV-Ray 2.2 format.  I believe AERO is
mirrored on wuarchive, though check version numbers with archie.  This system
looked to be pretty cool - you can simulate physically based phenomena.
There's also a paper about the system and the algorithms used.  Admittedly the
primitive set is limited (spheres and boxes), but Olli Vinberg
([e-mail]) pointed out that you can run the simulation, output
the results, and substitute the primitives with your own complex objects.
-EAH]

-------------------------------------------------------------------------------

A Brief Review of [an old] AERO, by Dave Negro ([e-mail])

My room-mate is running Linux and I learned about AERO last [school] year and
made him install it.  Haven't had any time to play with it this year, though.
I can tell you some of the things that I remeber from last year.

1) The simulations were great!  I found the emulation of real life was great
and could be used to make some great animations.

2) Editing was a little awkward but then again I wasn't able to fully get
accustomed to it myself.  There was of course the standard primitives (Sphere,
Cone, box etc)

3) Textures were lacking.  The selection and editing of textures left a lot to
be desired.

4) A separate .pov file is created for each frame!  There is no way to make an
include or anything for static objects.  Thus editing the files would be
nearly impossible to do with each frame!

5) Adding things to the scene but not with the tools in the AERO editor would
again be extremely difficult.

6) There were still some things that needed to be worked on like the open
dialog and save.  Biggies in my opinion.

Well, that is all I can remember for the moment.  But let me remind you that I
have not touched the program in a year, so I don't know if has changed at all,
and I wouldn't totally trust my memory either.

-------------------------------------------------------------------------------

Photon Tracing, by Chris Thornborrow ([e-mail]) and Greg Ward
    ([e-mail])

Chris Thornborrow writes:
OK onto the questions. I am writing a raytracer which does the following:

  a) Ordinary raytracing
  b) Distributed raytracing for lighting
  c) Path tracing (Kajiya)
  d) Photon tracing

  Now I need to be able to bias random vectors to do these *efficiently* but I
am unsure how to do this.  First off then, to generate a random direction
vector from a point, I generate a random vector in the unit cube and reject
those that lie outside the unit sphere.  This has a 50% rejection rate.  Can I
do better without approximations (I know about generating a 0..1 element and
then a random angle).

  The problem above appears compounded for a random vector within some solid
angle of another vector.  Currently I generate a random vector (as above) and
then reject ones out with the solid angle (using a dot product).  This is
awful.  Very small angles can be approximated by generating within a cone but
larger (say 20 solid degrees) give obviously biased distributions this way.

  Now my real problem.  Given an incident angle of a photon (ray) and the
surface normal and the BRDF, how can I generate a random reflection/refraction
angle that done many times would give the proper distribution defined by the
BRDF.  In other words, how can I bias the angle of perfect reflection in some
pseudo-random manner, so that a great number of samples of those directions
have the same distribution as the BRDF ?

  Obviously this is trivial for perfectly diffuse surfaces, its the others I
worry about :-).  I'd like to do this without rejection testing - is this even
possible without rejection testing ?

----

Greg Ward answers:

Let me start by saying that I'm not the world's foremost expert on Monte Carlo
sampling, but I have written a ray-tracer that does some of what you're
asking.  I assume you have read some books on Monte Carlo sampling already,
such as Rubenstein's 1981 treatise, "Simulation and the Monte Carlo Method"
(Wiley, NY).  Professor Pete Shirley of Indiana University has also written a
fair amount on Monte Carlo methods in ray tracing, though all I have in front
of me is something from his 1992 course notes on Global Illumination (course
18 that year), which I'm not sure you can find easily.  (I seem to remember
that someone put a bunch of Monte Carlo examples in a Graphics Gems book.  It
would have to be GG III, since that's the only one I don't have.)

The trick is to compute a cumulative probability function and invert it.  In
many cases, this can be done analytically.  In the case of the random
direction vector, it can even be solved by inspection.  You need only generate
two random angles, altitude and azimuth, and convert it back to a Cartesian
vector.  Rejection sampling is unnecessary.  Likewise, for the vector in the
solid angle of another vector, you can limit your polar angle to the cone you
have selected, 20 degrees in your example.

Arbitrary BRDF's are another matter.  Rejection sampling is the most general
method, but there is a more efficient way to go.  As you probably know, many
BRDF's are highly peaked, and using rejection sampling means you may have to
test hundreds of ray directions before you get one that isn't rejected.  The
more efficient approach is to generate a cumulative distribution table and
invert it.  I haven't done this myself, so excuse me if I'm a little foggy on
the details:

1.  Select a resolution limit for the polar and azimuthal angles in your ray
    direction calculation, somewhere around 5 degrees should be good.
    (This is the only real limitation to this technique.)

2.  Create a 3-dimensional table of real numbers.  The first dimension is the
    number of polar angles, the second dimension is the number of
    azimuthal angles, and the third dimension is the product of the two,
    i.e.  float cuml_prob[N][M][N*M];

3. For each reflected polar and azimuthal angle, do the following:

    3a. For each incident polar and azimuthal angle, compute the BRDF
        times the cosine of the polar angle times the sine of the
        polar angle and add it to a running total.  Store this sum at
        the appropriate point in the table created in step 2.

    3b.  Once done, your sum should equal the total reflectance, which
        should be less than one (but greater than 0!)  if you have a
        valid BRDF.  If it doesn't, you might want to report an error,
        but you can proceed with the calculation regardless.

4.  You have now filled a 6.5 Mbyte table, and this completes the
    initialization phase.  (Storing this sucker to disk wouldn't be a bad
    idea.)


Now, when you have to compute a ray direction, you look up the appropriate
table for this reflection angle, and:

5.  Compute a uniformly-distributed random number between 0 and 1 or 0 and the
    maximum value in this cumulative table, depending on whether the
    distribution is properly normalized and if you are accounting for
    reflectance with a multiplier or with pure Monte Carlo.

6.  Perform a binary search to find the value in the table that is closest to
    your random number, and determine the corresponding polar and
    azimuthal incident angles.  (This is the inversion step in this
    algorithm.)

7.  Jitter your sample uniformly within your 5 degree tolerance (or whatever
    you picked in step 1) to get the final ray direction.

8.  Trace that ray!

Obviously, the above algorithm could benefit from some refinement.  Firstly,
the precomputed table ends up being quite large.  The bigger your angle
tolerance, the smaller it will be, but I can never see it being very compact.
You can store the whole thing to disk, and just read in the section
appropriate to the reflection angle in hand when the time comes, and this will
save on your memory costs at the expense of one or two disk accesses.  Also,
the binary search (step 6) is fast but not free, and it may pay to invert your
table directly by computing azimuth and altitude angles corresponding to two
random variables.  This would require a little more thought, but I think it
could solve both of these problems.  The only catch is that you still want
some way of jittering the final result so as to avoid sampling a discrete set
of directions, and the distance between adjacent points in the table will vary
with such a scheme.  (Shouldn't be a problem, though.)

Has anyone implemented something along these lines who could help us out?  Pete?

-------------------------------------------------------------------------------

Faster Than POV-RAY 2.1, by Dieter Bayer ([e-mail])

[This bent my mind:  someone actually implemented my light buffer algorithm?
Astounding! -EAH]

A modified, sped-up and unofficial version of the
Persistence of Vision Ray-Tracer Version 2.2.


Faster than POV-Ray (FTPOV-Ray) speeds up calculation of images by using some
kind of direction cubes for primary rays (the vista buffer) and shadow rays
(the light buffer) at the cost of additional preprocessing time and greater
memory usage.  The bounding slab hierarchy used by POV-Ray is projected onto
the viewing plane and each point light source a priori.  Thus the number of
ray/slab-tests is reduced.  Furthermore some modules have been modified to
eliminate unnecessary calculations and automatic bounding has been improved.

The modified source code in the archive FTPV21S.ZIP may only be distributed
together with this text and the file POVLEGAL.DOC that is part of the official
POV-Ray package.  To use the source code you'll need the original POV-Ray 2.2
distribution.

WARNING!!!  If you use FTPOV-Ray you'll do it at your own risk!  And don't
forget that the POV-Ray team isn't responsible for this version.

I have uploaded the source code and executables for MS-DOS and OS/2 2.x to
ftp.informatik.uni-oldenburg.de and wuarchive.wustl.edu
(/pub/graphics/graphics/ray/pov/pov-dkb-archive/incoming).

-------------------------------------------------------------------------------

Z Buffer Based Rendering Program, by Raghu Karinthi ([e-mail])

[I tried this out and got some funky lighting problems (perhaps fixed by now),
but it seemed essentially sound.  It's nice to see a z-buffer for a switch
(lots harder to write than a basic ray tracer).  Hey, it reads NFF files, so I
like it ;-> -EAH]

We have developed a Z bufffer based rendering program in the West Virginia
University.  The key features of this program are:

(a) Reads a variant of the standard Neutral File Format (NFF) as input
(b) Outputs a 24 bit color TARGA file
(c) Uses accurate fixpoint arithmetic in all its calculations
(d) Works in X windows environment.  We have tested it on Sun Sparc machines.

This software is available via anonymous ftp.  The software includes two
sample files, including the teapot.  We would appreciate any feedback you can
give us on this software.  We are quite impressed by the quality of the images
produced.  Enjoy the use of this utility!

FTP from 157.182.44.36: pub/sources/ZRendv1.tar.Z

Below is a short description of the software.

Raghu Karinthi
Department of Statistics and Computer Science
Concurrent Engineering Research Center
West Virginia University
Morgantown, WV 26506-6506
Voice: [phone]
Fax:   [phone]
Email: [e-mail] OR [e-mail]


Description:

Often times, I have seen a question on the net for an accurate Z buffer
rendering implementation producing 24 bit color output along with facilities
for viewing the same.  We needed one ourselves as a benchmark for our work on
parallel rendering.  This document describes a program that we developed for
this purpose.  We have leveraged a number of public domain utilities and
defacto standards in our development, and hence this program does not have any
fundamental algorithms, it integrates existing ones effectively.

This describes briefly our implementation of the Z buffer rendering algorithm.
The rendering pipeline has the following steps:

1. Reading the input file.
2. Computing the light intensity at the vertices.  Later, Gouraud
   shading is used for interpolating the light intensity.
3. Computing the view transformation matrix.
4. Applying the view transformation to all the vertices
5. Rasterization, and writing to framebuffer.
6. Writing framebuffer to a TARGA file.

Subsequently, one can display the TARGA file, by invoking a separate utility
(included with this package).

This rendering program leverages of several public domain utilities.  The
matrix library is from the SPHIGS package from Brown University.  The view
transformation matrix also is computed using the code from the SPHIGS package.
Rasterization is based on fixed point arithmetic.  Fixed point arithmetic
library is from the directory "accurate_scan" from Graphics Gems III
contributed by Kurt Fleischer.  The rasterization code used in this program is
a modification of some code from the same source.  We compute 24 bit color
(R,G,B) at each pixel and write it to a TARGA file.  The functions to do write
in TARGA file format are from the "LUG" library due to Raul Rivero.  The
program "sx11" to display a TARGA file is also from the same library.  We have
extracted these two utilities from the LUG library and provided them in the
subdirectories "tga" and "sx11".

Input File Format:  The file format we use is a modification of the Neutral
File Format (NFF) described in the Standard Procedural Database (SPD) of Eric
Haines.  The modified NFF is described in the file called NFF in this
directory.  One can also look at the sample files.  In the NFF file format,
perspective projection is assumed.

-------------------------------------------------------------------------------

Gossamer, a Free Macintosh VR/3D Renderer, by Jon Blossom ([e-mail])

Gossamer 2.0, a real-time 3D walkthrough engine for the Macintosh, is now
available - for FREE!

Gossamer is a very fast, general 3D polygon rendering engine.  This version
radically improves speed over version 1.1, fixes a number of bugs, and focuses
on a more coherent user interface for "experimenters."

Version 2.0 also supports object and world files based on the Rend386 PLG and
WLD formats.  The Gossamer 2.0 package includes a number of sample worlds and
objects ported directly from the PC to the Macintosh, and there are others
available on bulletin boards, electronic services, and ftp sites all over.

The package is available for anonymous ftp from ftp.apple.com in the
pub/VR/graphics.systems directory.

If you have a Macintosh and are interested in 3D graphics, this will be well
worth your time.

The system requires a 68020 or better processor Mac running system 7 or system
6.x with 32-bit color QuickDraw.  A color display is nice but not necessary.

If you like Gossamer 2.0, please let me know!

-------------------------------------------------------------------------------

Antialiasing Issues, by Arijan Siska ([e-mail])

I want to get some attention to the (in my opinion) a very serious issue:
antialiasing.

When a raytracer with a finite resolution (obviously a resolution cannot be
infinite) renders an image jagged edges appear in picture (or in case of an
animation, when difference between two consecutive frames is large (when
objects move fast), animation tends to flicker).

These type of problems can be solved by two approaches:

- supersampling:  is a very very expensive method, since it involves much
extra (often unneeded) calculation, but generally it gives very good results
(image quality).

- adaptive sampling:  implies that there exists some criterion function, upon
which you can decide whether you should subdivide further to gain a more
precise answer or you should be satisfied with the approximation you already
have.  Note that in general there is no way to make this decision function
absolutely correct.  The best counterexample that I can think of is a thin
wire fence in front of uniform background.  If you use textures with rapid
changes it can happen that you subdivide (to the maximum level) 80% of the
pixels, which is effectively supersampling, but slower (you need to evaluate
criterion function all the time).  I don't see how some kind of preprocessing
could help you with criterion function, since all those reflections
refractions ....  are there.

----

Steven C. Demlow ([e-mail]) replies:

I played around with a variety of AA approaches in both my own ray tracer and
the public domain POV ray tracer.  I tried various derivations and
combinations of supersampling, stochastic jittering, adaptive methods, and
filtering.  For the animation project I was working on I ended up using 4x4
stochastically jittered grids on each pixel and a tent filter that extended
into the (cached, of course) grids of neighboring pixels.  I've been working
on using a hexagonal grid instead of a rectangular one (this gets tricky when
you try to overlap the arbitrarily-sized filtering grids of adjacent pixels).
The hex grid supposedly provides close to an optimal ray distribution for AA
purposes.

It sounds like you would do well to add filtering to your ray tracer - it can
help a lot.

The conclusion I came to, after eight months of rendering on a bunch of
HP7?0s, was that ray tracing is not the way to go to generate a lot of high-
quality images. :)  I love ray tracing but there are reasons that it sees
little use in production environments.

----

Andy Key ([e-mail]) replies:

I implemented Whitted Adaptive Supersampling as my anti-aliasing mechanism.
Really, the test of seeing whether to subdivide is tiny compared to the cost
of spawning a ray.  I support un-anti-aliased, and whitted.  I was going to
add unconditional-supersampling to improve the case when I have fine detail
textures, but I am not sure it will buy me a noticeable difference if I do.

-------------------------------------------------------------------------------

Microcosm, by Abe Megahed of Cosmic Software ([e-mail])

[I include this here as there is a free demo and images available.  It's a
nice system, allowing a wide range of interactive techniques with ray tracing,
and last I heard they were adding support for native graphics packages (e.g.
Starbase on HP's), multiple windows, and picking - they're up to version 1.4
or so by now.

This package was also the easiest system I ever dealt with for rendering on a
network (not that I've dealt with a lot, but...):  I simply started up the
daemons, let the software know which computers to use (HP workstations, in my
case), and let the software suck up resources and render at great speeds.
Impressively painless.  -EAH]


Microcosm, Version 1.2, New Product Announcement / Free Demonstration Version

A new version of Microcosm is being released for many popular platforms
including:

*  IBM PC / MS-DOS
*  DEC / Alpha
*  DEC / MIPS
*  HP 9000 Series 700 (Snake)
*  Sun Sparkstation
*  IBM RS 6000

Microcosm offers the highest quality rendering features such as ray tracing,
texture mapping, bump mapping, and Phong shading as well as interactive
animation capabilities.  A free demo version and over 100 example description
files of animations, simulations, interactive environments, objects, and
pictures is available via anonymous FTP.


What is Microcosm?

The Microcosm system is composed of a set of advanced 3D graphics routines
which is controlled by a simple, high level interpreted programming language
called SMPL for 'Simulation / Modeling Programming Language'.

This gives even the novice programmer the power and flexibility to easily
create graphics applications which could only previously be done with great
difficulty and expense in low level languages such as C.  Since the language
is interpreted, you may change things and immediately re-run your graphics
program without waiting for the computer to re-compile it.  It's fun and easy
- like programming an Apple II on steroids!

Most computer graphics intensive programs spend at least 95% of their time in
the rendering, so using the interpreter to control the renderer doesn't slow
the graphics down by more than 5% over a fully compiled program.


Features of Microcosm

Microcosm incorporates a number of totally new and innovative rendering
algorithms in a well integrated system.  Some interesting features are as
follows:

Rendering Features:
*    Shading Language
*    Surface Mapping
*    Procedural Textures
*    Real-Time Soft Shadows, Reflections, and Transparency / Refraction
*    Interactive Coarse Ray Tracing
*    Clean Line (Silhouette) Rendering Modes
*    Shaded Rendering Modes
*    Ray Tracing
*    A Choice of Projections
*    Hierarchy
*    Stereo Rendering

Modeling Features:
*    Procedural Modeling
*    Fractals
*    Variety of Primitives
*    Extensibility

Programming Features:
*    Easy-to-Read Syntax
*    Procedural, Block Structure
*    Flexible Parameter Passing
*    Built-in Data Types
*    Smart Arrays
*    Nested Comments


The demonstration version of Microcosm can be obtained by anonymous ftp at:
dpls.dacc.wisc.edu:  pub/graphics/mcm/mcm_demo.zip.  The demo version runs for
1 minute before quitting and also is unable to save files, so it can be used
only to preview simple renderings or animations.  A number of finished
renderings are available in mcm/images to illustrate the advanced rendering
capabilities of Microcosm.  Also provided free are about 100 example
description files to demonstrate the capabilities of Microcosm.

Please contact us for specific details about these or other platforms.  Any
other information, including price and/or ordering information can be obtained
as follows:

Cosmic Software Corp.
1413 Mound St.
Madison, Wisconsin
53711
[e-mail]
Tel: [phone]
FAX: [phone]

-------------------------------------------------------------------------------

Fisheye Lens Distortion, by Greg Ward ([e-mail])

Almost all wide angle photographic lenses have a bit of this, but in a
rendering program it is easier to avoid.

In a perfect perspective image, straight lines will always be straight, no
matter how wide the viewing angle becomes.  Viewing angles can never be equal
or greater than 180 degrees, however, because the arc tangent blows up.  A
full view angle close to the maximum will cause the center of the image to all
but disappear, and the view will be dominated by what surrounds the viewpoint.
(Try it, I guarantee you won't like it.)

In order to get a view of 180 degrees or greater, it is necessary to adopt
some sort of perspective distortion.  Most commercial fisheye lenses use a
distortion that causes distances from the center of the image to be
proportional to the geometric angle from the central line of sight.  Another
type of lens creates a view equivalent to taking a hemispherical image and
projecting it onto a plane, those such lenses are much harder to come by.

Another poster (Benjohn Barnes) mentioned that these effects are easier to
achieve in a ray tracing program, and he's probably right.  I didn't have too
much trouble implementing these view types in Radiance, and they come in quite
handy.  I can even render a 360 degree fisheye view, where the surround of the
circular image is actually a single point.  Neat trick.

P.S. When it comes right down to it, we all have eyes evolved from fishes.

-------------------------------------------------------------------------------

Optical Ray Tracers

[A common question on sci.optics is what ray tracers there are for lens
design.  Here are some cullings.  -EAH]

Mark Butterworth ([e-mail] - address now invalid)

Instead of driving this subject in to the ground, try the library at your
university and see if they have:

Modern Optical Engineering by Warren J Smith (he taught me) Applied Optics and
Optical Engineering by Kingslake volume 3 and volume 8 are good for this
subject

Warren Smith just published a new one (1992) that is a collection of lens
designs.  I forget the title, something like Optical Engineering:  a resource
manual.  Published by McGraw Hill.

The lenses in this book are also available on a disk library for the Genesee
ray tracing program.  Warren designed alot of the lenses used by Panavision,
just to mention one.

----

On the commercial side, an excellent package is ORA's CODE V (that's a Roman
numeral 5).  It's highly regarded and we've been happy with it.  They'll let
you have a free trial account on their dial-up VAX.

Optical Research Associates is in Pasadena,CA at [phone]

J. Sallay ([e-mail])

----

In article <[e-mail]>, [e-mail] says:
>Can anyone suggest a good commercial ray tracing program for general
>optical design. We are planning on spending a reasonable amount, like
>up to $1500.  We have only experience with much more expensive packages.

I don't think you can beat Zemax in this price range.  See their ad in
Photonics Spectra (p. 19 of the May '94 issue) or Laser Focus World (p. 7 of
May).  You can also send email to [e-mail] They will send a free demo
disk which is fully functional except that it won't save lenses.  They plan to
post it to ftp servers as soon as they get a readme done.  Caution:  Focusoft
is moving to Arizona and turning into Focus Software.  They hope to be
operational by 1 June.  The new phone numbers are:  voice:  602/749-5646 fax:
602/749-0987.  (Ken got tired of the California government.)

Steve Eckhardt ([e-mail])

----

If you have access to Mathematica (Wolfram Research Inc), there is a Notebook
called LensLab, available at MathSource.wri.com in directory
pub/Applications/Engineering/Other, with the item # 0204-343.  It is a decent
ray tracing program with an extensive set of functions for lenses, mirrors,
prisms etc..  It is relatively slow, unless you run Mathematica on a fast
Workstation, Quadra, Pentium,...  machine.

Rudolf Oldenbourg ([e-mail])

----

A good optical tracer is the new Mac version of Beam, from Stellar Software,
PO Box 10183, Berkeley, CA 94709, Fax [phone].  I helped with the beta
testing, so I know it's good.

A. David Beach ([e-mail])

----

For a freeware optics ray tracer, try irt52.zip in /pub/irt at
herx1.colorado.edu.  Use anonymous ftp to get this software.  It is written
for MS-DOS window and you need an unzip program to unzip it.

Djamshid Navabi ([e-mail])


I've tried it:  can't get past the demo example without a GPF that causes
Windows to quit to DOS the next time I try to run irt.  If I then try to run
Windows it tells me something gruesome like "invalid command processor" or
some such.  I'm trying to compile a more responsible set of actions to send to
the author but I wanted to mention it here to see if any one else has had the
experience or if it may be my system.

Neal E. Tornberg ([e-mail])

-------------------------------------------------------------------------------

Correcting Normal Direction, by Gavin Bell ([e-mail])

[There are a lot of polygonal models out there with inconsistent surfaces.
The problem is this:  you're given some random set of polygons and you want to
consistently orient them outwards so that your ray tracer or z-buffer can use
backface culling (i.e. ignore visible backfaces) and so speed performance.
Consistent orientation, that is, getting all the faces to be in clockwise
orientation, is fairly simple:  once you have the mesh of the object, each
shared edge must be traversed once in both directions.  So if two polygons
share an edge and traverse it in the same direction, then the order of
vertices of one of the polygons is reversed.  Continue the process until all
shared edges are traversed in both directions or until you get stuck (e.g. a
moebius strip doesn't work).  The next part is to know which side of the
polygon set is the outside.  This can certainly be done manually, but here's a
method of doing it automatically.  -EAH]


[someone (sorry, the name was deleted in the posting) writes:]
>> The user picks
>> a "Seed polygon" and I recursively "grow" a surface starting at
>> that polygon, a neighboring (child) polygon is considered to be flipped
>> if the child traverses the two shared vertices in the same
>> direction as the parent.

[someone else (sorry, name deleted) writes:]
>If you are not able to interactively pick such a seed polygon, there is an
>automatic way, but it takes time to write.  The idea is an extension of a
>point in polygon algorithm.  Basically, to find if a point is within a
>polygon, you can extend a ray from that point to infinity, if the ray crosses
>an even number of edges of the polygon, the point is outside (where 0 is
>defined to be even).  If it crosses an odd number, it is inside.
[I think the concept here was to take a vertex and see which side was outside
by ray tracing. -EAH]


A better method:

Consistently orient all of the polygons (you need to know which edges are
shared to do this, and this isn't possible for some objects-- e.g. mobius
strips, Klein bottles, etc).

Now, choose the point 'P' in the middle of the bounding box of the object.
For each triangle in the object, compute a signed volume for the tetrahedron
formed by the triangle and P.  Arrange your calculation so that the area will
be positive if P is left-hand-side of the triangle and negative if P is on the
right-hand-side of the triangle.  (if your triangle is ABC, then doing
(AB.cross.BC).dot.P will have this property).

Add up all of the volumes.  If the result is positive, then the normals are
oriented 'outside'.  If the result is negative, then the normals are oriented
'inside'.  If the result is zero or very close to zero, then the object is
flat or has just as many concave parts as convex parts.

This will always work for completely enclosed objects, and does the right
thing for surfaces-- it chooses the orientation that marks the surface 'most
convex'.  It works for self-intersecting objects.

Here's the code I use:
(If you have Inventor 1, this is in the 'ivnorm' code:)

    int i, j;

    int total_v = 0;
    SbVec3f average(0.0, 0.0, 0.0);

    for (j = 0; j < length(); j++)
    {
    Face *f = (*this)[j];
    if (f->degenerate) continue;

    for (i = 0; i < f->nv; i++)
    {
        average += verts[f->v[i]];
        ++total_v;
    }
    }
    average /= (float) total_v;

    float result = 0.0;

    for (j = 0; j < length(); j++)
    {
    Face *f = (*this)[j];
    if (f->degenerate) continue;

    for (i = 1; i < f->nv-1; i++)
    {
        SbVec3f v1 = verts[f->v[0]] - average;
        SbVec3f v2 = verts[f->v[i]] - average;
        SbVec3f v3 = verts[f->v[i+1]] - average;

        float t = (v1.cross(v2)).dot(v3);
        if (f->orientation == Face::CCW)
        {
        result += t;
        }
        else if (f->orientation == Face::CW)
        {
        result -= t;
        }
        else
        {
        assert(0);
        }
    }
    }
    return result > 0;

-------------------------------------------------------------------------------

Graphics Gems IV Table of Contents, by Paul Heckbert ([e-mail])

[I trimmed out the author names for the sake of space.  Incidentally, I've
found Gems IV to be subtly useful - don't judge the articles just by their
titles!  For example, "Detecting Intersection of a Rectangular Solid and a
Convex Polyhedron" by Ned Greene is actually about a method for determining if
a bounding box is visible within a viewing frustum, a very handy tool.  -EAH]

Below is the table of contents for "Graphics Gems IV".  This table also serves
as an index to the code in the FTP collection.  Note that every article has
text that appears in the book but not in the FTP archive, and some articles
contain no C or C++ code.

file or        book    chapter title and author
directory      chapter
------------------------------------------------------------
        I    POLYGONS AND POLYHEDRA
centroid.c    I.1    Centroid of a Polygon
convex_test/    I.2    Testing the Convexity of a Polygon
ptpoly_weiler/    I.3    An Incremental Angle Point in Polygon Test
ptpoly_haines/    I.4    Point in Polygon Strategies
delaunay/    I.5    Incremental Delaunay Triangulation
vert_norm/    I.6    Building Vertex Normals from an Unstructured Polygon
            List
        I.7    Detecting Intersection of a Rectangular Solid and a
            Convex Polyhedron
collide.c    I.8    Fast Collision Detection of Moving Convex Polyhedra

        II    GEOMETRY
        II.1    Distance to an Ellipsoid
dist_fast.c    II.2    Fast Linear Approximations of Euclidean Distance in
            Higher Dimensions
outcode/    II.3    Direct Outcode Calculation for Faster Clip Testing
sph_poly.c    II.4    Computing the Area of a Spherical Polygon
        II.5    The Pleasures of `Perp Dot' Products
        II.6    Geometry for N-Dimensional Graphics

        III    TRANSFORMATIONS
arcball/    III.1    Arcball Rotation Control
        III.2    Efficient Eigenvalues for Visualization
inv_fast.c    III.3    Fast Inversion of Length- and Angle-Preserving Matrices
polar_decomp/    III.4    Polar Matrix Decomposition
euler_angle/    III.5    Euler Angle Conversion
        III.6    Fiber Bundle Twist Reduction

        IV    CURVES AND SURFACES
data_smooth/    IV.1    Smoothing and Interpolation with Finite Differences
        IV.2    Knot Insertion using Forward Differences
        IV.3    Converting a Rational Curve to a Standard Rational
            Bernstein-Bezier Representation
curve_isect/    IV.4    Intersecting Parametric Cubic Curves by Midpoint
            Subdivision
patch_conv.C    IV.5    Converting Rectangular Patches into Bezier Triangles
nurb_polyg/    IV.6    Tessellation of NURB Surfaces
        IV.7    Equations of Cylinders and Cones
implicit.c    IV.8    An Implicit Surface Polygonizer

        V    RAY TRACING
        V.1    Computing the Intersection of a Line and a Cylinder
ray_cyl.c    V.2    Intersecting a Ray with a Cylinder
vox_traverse.c    V.3    Voxel Traversal along a 3D Line
multi_jitter/    V.4    Multi-Jittered Sampling
minray/        V.5    A Minimal Ray Tracer

        VI    SHADING
        VI.1    A Fast Alternative to Phong's Specular Model
        VI.2    R.E versus N.H Specular Highlights
        VI.3    Fast Alternatives to Perlin's Bias and Gain Functions
        VI.4    Fence Shading

        VII    FRAME BUFFER TECHNIQUES
        VII.1    XOR-Drawing with Guaranteed Contrast
        VII.2    A Contrast-Based Scalefactor for Luminance Display
dyn_range/    VII.3    High Dynamic Range Pixels

        VIII    IMAGE PROCESSING
emboss.c    VIII.1    Fast Embossing Effects on Raster Image Data
coons_warp.c    VIII.2    Bilinear Coons Patch Image Warping
convolve.c    VIII.3    Fast Convolution with Packed Lookup Tables
thin_image.c    VIII.4    Efficient Binary Image Thinning using Neighborhood Maps
clahe.c        VIII.5    Contrast Limited Adaptive Histogram Equalization
mrsfoley.im    VIII.6    Ideal Tiles for Shading and Halftoning

        IX    GRAPHIC DESIGN
        IX.1    Placing Text Labels on Maps and Diagrams
graph_layout/    IX.2    Dynamic Layout Algorithm to Display General Graphs

        X    UTILITIES
trilerp.c    X.1    Tri-linear Interpolation
interp_fast.c    X.2    Faster Linear Interpolation
vec_mat/    X.3    C++ Vector and Matrix Algebra Routines
GraphicsGems.c    X.4    C Header File and Vector Library

-------------------------------------------------------------------------------

Beyond Graphics Gems, by Paul Heckbert ([e-mail])

[From the Preface of Gems IV, which Paul posted to the net. -EAH]

In addition to the "Graphics Gems" series, there are several other good
sources for practical computer graphics techniques.  One of these is the
column ``Jim Blinn's Corner'' that appears in the journal "IEEE Computer
Graphics and Applications".  Another is the book "A Programmer's Geometry", by
Adrian Bowyer and John Woodwark (Butterworth's, London, 1983), which is full
of analytic geometry formulas.  A mix of analytic geometry and basic computer
graphics formulas is contained in the book "Computer Graphics Handbook:
Geometry and Mathematics" by Michael E.  Mortensen (Industrial Press, New
York, 1990).  Another excellent source is, of course, graphics textbooks.

-------------------------------------------------------------------------------

Radiosity vs. Ray Tracing, by Rico Tsang ([e-mail])

[I made a few minor fixes, but otherwise this was a nice cheat-sheet summary
of the functional (vs. algorithmic) differences between meshed radiosity and
classical ray tracing.  -EAH]

    Radiosity                     Ray Tracing

work best to model -            work best to model -

1. Area light sources            1. Point light sources
2. Diffuse reflections            2. Specular reflections
3. Color bleeding            3. Refraction effects
4. Soft shadows                4. Sharp shadows



Limitations of Radiosity
========================

1.  All surfaces are assumed to be perfect diffuse reflectors.
2.  Specular reflections and transparent effects cannot efficiently modelled.
3.  Time & storage consuming.  For n surface patches in a scene, you need to
    calculate and store n^2 form factors.  If you use the 'progressive
    refinement' radiosity method or hierarchical radiosity, you can minimize
    the storage requirement for storing the form factors.


Advantages of Radiosity
=======================

1.  The calculation of radiosities is view-independent.  Once it does so, a
    view of the environment can be generated with relatively little effort
    (i.e.  via gouraud interpolation) for any camera position.

    ==> provides the capability of interactive walkthrough

2.  With the progressive refinement method, a geometrically correct view of
    the environment can be displayed almost immediately.

-------------------------------------------------------------------------------

ACM SIGGRAPH Online Bibliography Updated, by Frank Kappe
    ([e-mail])

This is to announce that the well-known ACM SIGGRAPH Online Bibliography (that
holds some 16,000 references to computer grahics literature) has been updated.
The ACM SIGGRAPH Online Bibliography Database was compiled by Stephen N.
Spencer ([e-mail]) with help from various contributors.

The data set is available through the Hyper-G server of the Graz University of
Technology either by WWW protocol:
    http://www.tu-graz.ac.at/CSIGGRAPHbib

or by Gopher protocol:
    gopher://gopher.tu-graz.ac.at/11SIGGRAPHbib

or using a Hyper-G native client such as Harmony (for UNIX/X-Windows), which
works best, of course. If you are interested in obtaining a copy of Harmony
please look at
    ftp://iicm.tu-graz.ac.at/pub/Hyper-G/Harmony

for downloading instructions. People without clients may also try
    telnet://info.tu-graz.ac.at

to access the Hyper-G server of Graz University of Technology.

More information about the the ACM SIGGRAPH Online Bibliography Project can be
reached from the URLs mentioned above.

[The bibliography can be FTP'ed from siggraph.org: /publications/bibliography
-EAH]

-------------------------------------------------------------------------------

How to be Notified of New POV Releases

The official POV distribution site is ftp.uwa.edu.au.  This site has become
quite active and holds many POV scene files and utilities as well as POV
itself.

As an adjunct to this site, a mailer has been set up which permits file
requests to be made by email, and which also manages a mailing list.

The site and the list itself is maintained by a member of the POV-Team
[Chris Cason ([e-mail])].

You can request that your name be placed on one or both of the POV mailing
lists.  These are not normal mailing lists in that you cannot submit messages
for them ; only the POV-Team can.  The lists are as follows -

  ANNOUNCE    Used when new releases of POV are made. This includes POV-related
          items from the POV-Team, such as the soon-to-be released hypertext
          help system.

  NEWS        Used to send new issues of POV-News and anything else relevant
          to POV, such as new publications, magazine articles, etc.

Volume on both of these lists will be extremely low ; perhaps only one message
per month if even that.  This is the easiest way for POV users to be informed
of patches, bug fixes, new releases, new features, release dates for new
versions and the actual release of new versions.

To join these lists, mail a message to -

  [e-mail]

The subject of the message is unimportant.

In the body of the message, place the commands -

  JOIN ANNOUNCE         (to join the announce mailing list)
  JOIN NEWS             (to join the news mailing list)

    - or -

  JOIN ALL              (to join both)

You should receive a reply indicating that your request was successful.
If you don't, please try again. For more information, please mail the above
address with a message containing the word -

  HELP

on the first line.

-------------------------------------------------------------------------------

PoVSB Windows-based Modeler v0.85, by Jeff Hauswirth
    ([e-mail])

What's new-

    Bezier Surfaces.
    A help file.

PoVSB is now shareware at $30.  Everything is functional except saving the
Bezier objects.  Exporting Bezier objects to PoV is functional.

PoVSB is a Windows based modeler for the Persistence of Vision Raytracer.  The
goal of PoVSB is to allow users of PoV to quickly and easily design scenes in
the Windows environment with true camera preview of the scene so no guess work
is involved.

I would like to collect a bunch of PoVSB example files to include with PoVSB
and to also make them available via ftp so other people can use them.  If
anyone is interested, just e-mail me your example files to include with PoVSB.

I have included two example files- teacup and satellite.  Try rendering the
satellite with and without the MB PoV option.  With the MB option it was 6
times faster, if I remember right.

I would like to get some feedback from all the people with PoVSB, which I
think is up near ~350.  I want to know what new features you would like.

PoVSB has been tested on 386-SX-4M up to 486-66-16M.  The 386-SX had trouble
with loading the teacup example file.  Other than that I have found no
problems.

Features:

    Four view of scene:
    3 ISO views, 1     Camera view
    Objects supported:
    Sphere, Box, Plane, Cone, Cylinder, Torus,
    Height Fields, Bezier Surfaces.
    CSG:  Union, Merge, Intersection, Difference
    RAW:  Only flat triangle output available (for now).

    Interactive transformations of objects

    Lights: Point, Spot

    Multiple Layers

    Textures:    Customizable, add your own textures


How to get PoVSB:

ftp to: vincent.iastate.edu
Username: anonymous.jhaus
Password: [e-mail]

If you already have PoVSB you only need to get povsbXX.zip,
Otherwise you need to get povsb.zip.

-------------------------------------------------------------------------------

Porting Rayshade, PBM, etc from Unix to DOS, by Mike Castle
    ([e-mail])

Amazingly enough Jasen M. Mabus said:
> Where can I find PBMtools, a preprocessor implementor, and CoProcessor
> emulator for 386 in DOS executable?

I ported pbmplus using djgpp a couple years back.  djgpp is a development
environment by DJ Delorie that includes a homegrown dosextender called "go32",
gcc/g++ compilers, flex, bison, assorted binary utilities (ar, ld, nm, etc),
make, and so on.  This environment is an eclectic mix of unixish and dosish
calls, but is a very workable environment.

My port of pbmplus can be found on any simtel archive in graphics/pbmpl19d.zip
(such as oak.oakland.edu in pub/msdos/graphics/pbm...).

djgpp can also be found in the djgpp dir (pub/msdos/djgpp on oak).  You could
scan cpp from the djgpp distribution, and have a working preprocessor.

I included the then current emu387 387 emulator from the djgpp package in my
pbmplus port, however, that was some time ago.  There are newer and better
emulators that can be found in the djgpp archives.  Of course, the emu387 and
wmemu387 (another emulator compatible with go32, but done by someone else)
will only work with go32 binaries.

The go32 included with my pbmplus port is out of date, and you may want to get
the most recent go32.exe from the djgpp packages.  you may also have to run a
program called 'dpmifix' on the pbmplus binaries to get things working
correctly (i'm not sure as i don't use dos much anymore, having switched to
os/2, and so i'm not quite up on djgpp and stuff, and i don't even have my own
copy of my pbmplus port anymore so....).

btw, i used the djgpp package to port rayshade quite some time ago, but as
there was already a 386 port done using a commercial dos extender, never made
it available.  The port was very straight forward, and only required the
normal flex/lex bison/yacc fixes (such as rayshades misuse of the yyline
action), 8.3 file name fixups, and binary mode stdin/stdout.  It worked very
well, including support for RLE files (i ported the URT as well), cpp, and so
on.

-------------------------------------------------------------------------------

REYES & Patents, William C. Archibald ([e-mail])

> Is REYES patented?

Pixar holds three (at last count) patents (including US Patent Number
5,025,400) on "Pseudo-random point sampling techniques in computer graphics".
This includes claims that cover stochastic ray-tracing as well as what you are
probably referring to by REYES.


> If so, what part of the algorithm?

Clearly stochastic sampling techniques as they apply to computer graphics.


> Is one allowed to implement the algorithm?

I believe that in the U.S.A. one is allowed to implement the algorithm for
the purposes of studying it and trade-offs that may be involved.  One is not
allowed to redistribute any implementations without permission, as that is the
very thing that patent law is set up to protect against.

[and in a separate note by the same author:]

In patent 5,025,400 the claims go on for 4.5 pages (9 columns) of legalese,
and they seem to pretty much make claim to usage w/ respect to lens effects
(depth of field), motion blur (temporal jitter), penumbra and other soft
shadow effect, and just about every variation of jittering reflected rays of
objects for any reason you might imaging.  I've not been able to really pin
down good, old-fashioned anti-aliasing anywhere in the claims though...

-------------------------------------------------------------------------------

Going from AutoCAD and 3DS into Ray Tracing, by Sean Ross ([e-mail])

Well, for starters, saying one raytracer is "better" than the others is
guaranteed to cause a flame fest of amazing proportions, so I will just tell
you about my experience so far and let you make your own determinations.

What I discovered, from following this group for a while and reading the
"Mini-FAQ", is that there are quite a few different raytracers around with
different capabilities.  I found Vivid a bit rough to get started with, and
therefore tried PoVray, it's been great so far.  I find it easy to use because
the language is fairly intuitive.

What has turned out to be easiest for me to create good raytracings with a
fairly short learning curve is using the following method:

Use AutoCAD Release 12 with AME to create the initial objects.  AME allows
very easy creation of complex 3d objects using addition, subtraction,
intersection, etc.

Export the finished objects into 3d Studio (I'm using ver 1) to set the camera
and lighting.  Assign surfaces to all objects with standard names like
"surface1" etc.

(If you don't have access to AutoCAD and/or 3D Studio, try using Moray, it's
shareware ($50) and seems to be easy to use and well supported)

Use 3DS2POV program to convert the 3d studio file to a PoV file and include
file.

Edit the resulting .pov file and replace 3d studio's surfaces with the much
better surfaces included with pov.  (I've also found it very simple to modify
these surfaces to do almost anything.)

Render sample files using a small size (160 x 100) and adjust any settings you
don't like in the .pov file.

Start the final rendering with high quality, anti-aliasing, and a large size,
and plan on not using your system for a while if you're using a lowly 486DX266
w/8MB like me.  My finished quality renderings generally take about 8 hours to
process for a 2048 x 2048 image, and I consider these images to be fairly
simple (not too many complex objects).

If the above doesn't sound like too much work, give PoVray a try, it's given
me very good results with a negligible learning curve.  I plan on trying out
some of the others available, especially Radiance because of its radiosity
features, but I haven't got around to it yet.

If anyone else has any suggestions on how I might improve upon the methods I
described above, I would be greatly interested.

By the way, just one warning:  after I started creating these images, I find
myself dedicating a pretty good amount of time to it, I think it's pretty
addictive, so be careful.

-------------------------------------------------------------------------------

Computer Lego Modeling, by Paul Gyugyi ([e-mail])

Check out the files on earthsea.stanford.edu in the ~ftp/pub/lego/cad/click
and ~ftp/pub/lego/cad/rayshade directories.  They include:

1) A library of high-detail shape definitions for Rayshade, a 3D modelling/ray
    tracing program (legolib.ray).

2) A definition of a language, LADEL, for specifying brick types and
    positions.

3) A compiler to convert LADEL files to rayshade input files that use the
    above library of brick definitions.

4) A new extension to the compiler that generates a 3D wire-frame image from a
    LADEL file.  You can fly around and rotate it.  It uses an Xwindows
    library that is similar to GL, called VOGL, and runs on UN*X machines.

There is _no_ documentation for most of this stuff, but if you want to try it
out, email me any questions you have and I'll start creating a how-to.

-------------------------------------------------------------------------------

Rowe's Ray Tracing World BBS, by Harry Rowe ([e-mail])

phone: (513) 866 - 8181 v.32bis (Dayton, OH)

I have a new ray tracing BBS.  No fees.  It does require user to have Windows
3.1 and special client software which can be downloaded on the first call.  It
is Excalibur (tm) based and is a 100% Windows GUI BBS.  I only carry
DOS/Windows tracers, but also have tons of objects, textures, converters, etc.
I have most of what Compuserve GRAPHDEV has in the way of RT utilities.  I
primarily support Polyray v1.7 and Imagine 3.0 for DOS.  We also have expert
3DS users.

[Harry has recently made a nice 500+ line summary guide to the major POV
utilities, with 4-15 lines about each one.  I won't put it here, but contact
him for where it is (or if all else fails, contact me and I'll send you the
old copy I have).  -EAH]

-------------------------------------------------------------------------------

On Using BSP trees, by Benton Jackson ([e-mail])

[BSP trees are a nice technique for doing 3D and avoiding z-buffering in
games.  You partition a static environment with a binary-tree hierarchy of
cutting planes, classifying everything in the node as in front of or behind
the plane of some given polygon (and splitting things cut by the plane).  Note
that this is different than the BSP trees used in ray tracing, where the planes
are independent of the polygons and are essentially a more flexible octree
like structure.  Worth understanding in general.  -EAH]

>Do I have to build a new BSP tree for all visible polygons at each frame
>redraw?  This is what I suspect, but I can't help thinking that there is
>something more I could do to improve calculation times if I had separate BSP
>trees for each shape.

I'm surprised that isn't in the FAQ.  That's the whole point of BSP trees!
Based on the current viewpoint, if it is in front of the root face, draw the
back tree, then the face, then the front tree.  This works since that face is
guaranteed to be in front of everything on one side of the tree, and behind
everything on the other side.  Which way you go depends on the viewpoint.
Cool, huh?  Like this:

DrawBSP(tree B) {
   if (!B) return;
   if (in_front_of(viewpoint,B->face) {
      DrawBSP(B->back);
      DrawFace(B->face);
      DrawBSP(B->front);
   } else {
      DrawBSP(B->front);
      DrawFace(B->face);
      DrawBSP(B->back);
   }
}

This doesn't completely depth sort the faces.  But you don't have to!  You
just need to ensure that a face that obscures another faces is drawn in the
correct order.  That's what this does.

If an object moves, then the tree has to be rebuilt.  I think there is a way
to merge BSP trees, but I don't know how.  Anybody?

-------------------------------------------------------------------------------

Books about Commercial Renderers, by Don Lewis, Jimbo and Yury German

3D Studio 3.0:

Don Lewis ([e-mail]) writes:

Try Inside 3D STUDIO Release 3, comes with a CDROM of sample DXF's and images
and maps.  Listed as:
        ISBN 1-56205-075-3
price $49.95 USA / $65.95 CAN / L46.99 Net U.K. (inc of VAT)

About the CD:
Meshes, Texture maps, Bump maps, Graphics file format conversion utility,
Special effects filters, Utilities for image viewing, printing, and conversion
(windows and dos), An updated Autodesk animation player, Files for exercises
in the book, etc ...

I like the book and a lot applies to 3DStudio 2.0 as well.

----

Jimbo ([e-mail]) writes:

Inside 3D Studio:
-----------------

Author(s):      Steven D. Elliott
        Phillip L. Miller
        Gregory G. Pyros

ISBN:        1-56205-075-3

Publishers:    New Riders Publishing.

An excellent book including a CD, unfortunately doesn't include
the IPAS routines mentioned numerous times throughout.


3D Studio Applied:
-------------------

Author(s):      Nancy Fulton

ISBN:        0-929870-24-7

Publishers:    Advanstar Communications Inc.

--------

Imagine system:

>     Question: My uncle has this and would like to know
> if there are any other references for IMAGINE that are a
> bit easier to understand for those less technologically literate.

Yury German ([e-mail]) writes:

    Yes, there is a great book, it's called Understanding Imagine.  Steve
Worley is the author.  Now the book is "Understanding Imagine 2.0" for the 2.0
version.  In a few months the book will be out for "Understanding Imagine 3.0".

    The first book was done with the Amiga computer in mind.  The 3.0 book
might be done for both computers.  If you want you can email Steve at
[e-mail] for information.

    The books are great with alot of humor and all the things needed to
make manuals easy and understandable.

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END OF RTNEWS