comp.graphics.misc FAQ

Last update: 04Mar97

This document answers a number of the most frequently asked questions about graphics on the Internet. To avoid wasting bandwidth and as a matter of politeness please look for the answer to your question in this document BEFORE posting to comp.graphics.misc.

If your copy of the FAQ is more than a couple of months old, you may want to seek out the most recent version. The latest non-HTML version of this FAQ is always available on rtfm.mit.edu as /pub/usenet/news.answers/graphics/faq.

In case you're reading the ASCII version of the FAQ, the HTML version is at http://www.primenet.com/~grieggs/cg_faq.html.

Send your updates to me at grieggs@primenet.com. I reserve the right to reject or modify submissions based on my interpretation of the role of the FAQ.

Contents

Editorial

It's been a long time since the last update. I am sorry about that, but my life has been very busy since then. Things seem a little quieter now, so hopefully updates will happen a bit more frequently.

Assume that any updates sent to me since the last FAQ update have been lost one way or another and need to be resubmitted.

_john

Copyright

 The comp.graphics.misc FAQ is Copyright (c) 1995 John T. Grieggs. It may be freely distributed electronically on the Usenet and via the Internet, but may not be reprinted in whole or in part in non-electronic form without prior permission of the editor (me).

What this means in English is that if you want to reprint or quote the FAQ or part of it in a book or on a CD-ROM, I want to know about it, in advance, and reserve the right to put conditions on such activities. To date I have allowed 6 or 7 authors to do what they wanted, and refused permission to 1 blatantly tacky commercial venture.

Links to the HMTL version are welcome and even encouraged. The canonical location is http://www.primenet.com/~grieggs/cg_faq.html.

Changes since last revision

 The FAQ has been comatose, but is now awake.

Don't forget to send your contributions to grieggs@primenet.com! If you just post, I may not see it for one reason or another.

Other Graphics-related FAQs and FAQ-like documents

 The comp.graphics.misc FAQ attempts to cover a wide range of material. If you don't find what you need here, try one of these more focused documents.

comp.graphics.algorithms FAQ
Maintained by Jon Stone (jdstone@destin.dazixco.ingr.com), the comp.graphics.algorithms FAQ contains questions and answers about computer graphics algorithms. There is some overlap between this document and the one you are reading, for historical reasons. It is available on rtfm.mit.edu as /pub/usenet/news.answers/graphics/algorithms-faq.

comp.graphics.animation FAQ
Maintained by Francisco X DeJesus (dejesus@vislab.navy.mil), the comp.graphics.animation FAQ contains questions and answers about computer graphics animation. He maintains a HTML version at http://www.ridgecrest.ca.us/fx/cga-faq.html. The non-HTML version is still available on rtfm.mit.edu as /pub/usenet/news.answers/graphics/animation-faq.

Graphics File Formats FAQ
Maintained by James Murray (jdm@netcom.com), the Graphics File Formats FAQ contains information on graphics file formats, including raster, vector, metafile, PDL, 3D object, animation, and multimedia formats. It is available on rtfm.mit.edu as /pub/usenet/news.answers/graphics/fileformats-faq.

Color Space FAQ
Maintained by David Bourgin (david.bourgin@ufrima.imag.fr), the Color Space FAQ contains questions and answers about colors and color spaces. It is available on rtfm.mit.edu as /pub/usenet/news.answers/graphics/colorspace-faq.

Frequently Asked Questions about Gamma and Colour
Charles Poynton has written FAQs on Gamma and Color Spaces. His FAQs are available from his web page, http://www.inforamp.net/~poynton/ in a variety of formats. Text versions may be obtained at ftp.inforamp.net in the /pub/users/poynton/doc/colour directory.

Computer Graphics Resource Listing
Maintained by Nick Fotis (nfotis@theseas.ntua.gr), the CGRL contains questions and answers about general graphics documents, sort of like this document. It came into existence for political reasons. There is no clear division of responsibility between his document and mine, but I do tend to keep this one a bit more terse and free of commercial material. As a result, the CGRL is much larger and is stored in six parts. You can get the parts at rtfm.mit.edu as /pub/usenet/news.answers/graphics/resources-list/part[1-6], or get the auto-HTMLed version at http://www.cis.ohio-state.edu/hypertext/faq/usenet/graphics/resources-list/top.html.

General References

Books

Eratta

 Errata for "An Introduction to Ray Tracing" is available on wuarchive.wustl.edu as /graphics/graphics/books/erratas/IntroToRt.

Errata for "Digital Image Warping" is available on wuarchive.wustl.edu as /graphics/graphics/books/erratas/Digital-Image-Warping.

Errata for "Photorealism and Ray Tracing in C" is available on wuarchive.wustl.edu as /graphics/graphics/books/erratas/Photorealism-and-ray-tracing-in-C.

Errata for the "Graphics Gems" series are available on wuarchive.wustl.edu in /graphics/graphics/books.

Other

An automatic mail handler at Brown University allows users of "Computer Graphics: Principles and Practice," by Foley, van Dam, Feiner, and Hughes, to obtain text errata and information on distribution of the software packages described in the book. Also, users can send the authors feedback, to report text errors and software bugs, make suggestions, and submit exercises. To receive information describing how you can use the mail handler, simply mail graphtext@cs.brown.edu and put the word "Help" in the Subject line. Use the Subject line "Software-Distribution" to receive information specifically concerning the software packages SRGP and SPHIGS.

All C code from the "Graphics Gems" series is available via anonymous ftp from princeton.edu. Look in the directory pub/Graphics/GraphicsGems for the various volumes (Gems, GemsII, GemsIII, GemsIV), and get the README file first.

A list of computer graphics, computational geometry and image processing journals is available from Juhana Kouhia, jk87377@cs.tut.fi.

Specific References

Ray-Tracing and Global Illumination

 Rick Speer maintains a cross-indexed ray-tracing bibliography. The bib is in the form of a PostScript file. The printout is 41 pages long. It may be found on wuarchive.wustl.edu as /graphics/graphics/bib/RT.BIB.Speer/speer.rt.bib.ps.Z, and on plaza.aarnet.edu.au as /graphics/graphics/bib/RT.BIB.Speer/speer.rt.bib.ps.gz.

While useful, this document has not been updated since 1991. Is there a more recent version out there somewhere that I don't know about?

Ian Ashdown maintains ray tracing and radiosity/global illumination bibliographies. These are in "refer" format, and so can be searched electronically (a simple awk script to search for keywords is included with each). The bibliographies have been combined, and are available on hobbes.lbl.gov as /pub/doc/RadBib95.Z. There are also some other interesting papers in the same directory.

Tom Wilson (twilson@dab.ge.com) has collected over 300 abstracts from ray tracing related research papers and books. The information is essentially in plaintext, and Latex formatting programs are included. This collection is available at most of the sites mentioned above as "rtabs.*".

Graphics File Formats

Spatial Data Structures

PEX and PHIGS

 There is an analysis of OpenGL vs. PEX, Analysis of PEX 5.1 and OpenGL 1.0, Allen Akin, available on sgi.sgi.com as /sgi/opengl/doc/analysis.ps.Z.

OpenGL

There is an analysis of OpenGL vs. PEX, Analysis of PEX 5.1 and OpenGL 1.0, Allen Akin, available on sgi.sgi.com as /sgi/opengl/doc/analysis.ps.Z.

Morphing

Warping is the deformation of an image by mapping each pixel to a new location. Morphing is blending from one image or object to another one. Valerie Hall has written an excellent introduction to warping and morphing. This is available for anonymous ftp from marsh.cs.curtin.edu.au in the directory pub/graphics/bibliography/Morph. There are three files:

The files are compressed, so you must use binary transfer and uncompress them afterwards.

The definitive book on the topic:

Radiosity

 Radiosity is a technique for generating very realistic scenes using global illumination (a radiative transfer problem).

How do I ...

 This section provides brief answers to some of the most frequently asked how-to questions. More verbose answers can generally be found in the literature mentioned in the General References section.

How do I draw 3D objects on a 2D screen?

 There are many ways to do this. Some approaches map the viewing rectangle onto the scene, by shooting rays through each pixel center and assigning color according to the object hit by the ray. Other approaches map the scene onto the viewing rectangle, by drawing each object into the region, keeping track of which object is in front of which.

The mapping mentioned above is also referred to as a "projection", and the two most popular projections are perspective projection and parallel projection. For example, to do a parallel projection of a scene onto a viewing rectangle, you can just discard the Z coordinate (divide by depth), and "clip" the objects to the viewing rectangle (discard portions that lie outside the region).

For details on 3D rendering, the Foley, van Dam, Feiner and Hughes book, "Computer Graphics: Principles and Practice" would be a good place to start reading. Chapter 6 is "Viewing in 3D", and chapter 15 is "Visible-Surface Determination". For more information go to chapter 16 for shading, chapter 19 for clipping, and branch out from there.

How do I quantize 24-bit images down to 8 bits?

Find a copy of "Color Image Quantization for Frame Buffer Display" by Paul Heckbert, SIGGRAPH '82 Proceedings, page 297. There are other algorithms, but this one works well and is fairly simple. Implementations are included in most raster toolkits (check out the various free image manipulation software available).

A variant method is described in "Graphics Gems", p. 287-293 (but no code), and there is further information in "Graphics Gems II", p. 126-133 (code available online but not in book). Spencer Thomas' article in Gems II on Efficient Inverse Color Map Computation (p. 116-125) is also relevant, and code is provided in the book and online, as well as in the Utah Raster Toolkit. Note that the code from the "Graphics Gems" series is all available from an FTP site, as described above.

Also check out John Bradley's "Diversity Algorithm", which is incorporated into the xv package and described in the back of the manual.

The ImageMagick package contains another quantizing algorithm which is presented as "doing a better job than the other algorithms, but slower".

Ian Ashdown (Ledalite@mindlink.bc.ca) is maintaining a bibliography of color quantization papers and articles that is available at hobbes.lbl.gov as /pub/doc/cquant95.Z. It includes both the original presentations of the algorithms and their implementation in popular computer magazines such as Dr. Dobb's Journal and The C/C++ Users Journal.

How do I convert color to grayscale?

The NTSC formula is:

luminosity = .299 red + .587 green + .114 blue

For additional information, please refer to the Color Space FAQ.

How do I convert grayscale to black & white?

The definitive book on the topic:

But before you go off and start coding, check out the variety of free image manipulation software available. Almost all of the packages mentioned can do some form of gray to b&w conversion.

For additional information, please refer to the Color Space FAQ.

How do I rotate a raster image by an arbitrary angle?

The obvious but wrong method is to loop over the pixels in the source image, transform each coordinate, and copy the pixel to the destination. This is wrong because it leaves holes in the destination. Instead, loop over the pixels in the destination image, apply the *reverse* transformation to the coordinates, and copy that pixel from the source. This method is quite general, and can be used for any one-to-one 2-D mapping, not just rotation. You can add anti-aliasing by doing sub-pixel sampling.

However, there is a much faster method, with antialising included, which involves doing three shear operations. The method was originally created for the IM Raster Toolkit; an implementation is also present in PBMPLUS. Reference: A Fast Algorithm for Raster Rotation", by Alan Paeth (awpaeth@watcgl.waterloo.edu) Graphics Interface '86 (Vancouver). An article on the IM Raster Toolkit appears in the same journal. An updated version of the rotation paper appears in "Graphics Gems" under the original title.

How do I draw a circle as a Bezier (or B-spline) curve?

The short answer is, "You can't." Unless you use a rational spline you can only approximate a circle. The approximation may look acceptable, but it is sensitive to scale. Magnify the scale and the error of approximation magnifies. Deviations from circularity that were not visible in the small can become glaring in the large. If you want to do the job right, consult the article:

"A Menagerie of Rational B-Spline Circles" by Leslie Piegl and Wayne Tiller in IEEE Computer Graphics and Applications, volume 9, number 9, September, 1989, pages 48-56.

For rough, non-rational approximations, consult the book:

Computational Geometry for Design and Manufacture by I. D. Faux and M. J. Pratt, Ellis Horwood Publishers, Halsted Press, John Wiley 1980.

For the best known non-rational approximations, consult the article:

"Good Approximation of Circles by Curvature-continuous Bezier Curves" by Tor Dokken, Morten Daehlen, Tom Lyche, and Knut Morken in Computer Aided Geometric Design, volume 7, numbers 1-4 (combined), June, 1990, pages 33-41 [Elsevier Science Publishers (North-Holland)]

How do I tell whether a point is within a planar polygon?

Consider a ray originating at the point of interest and continuing to infinity. If it crosses an odd number of polygon edges along the way, the point is within the polygon. If the ray crosses an even number of edges, the point is either outside the polygon, or within an interior hole formed from intersecting polygon edges. This idea is known in the trade as the Jordan curve theorem; see Eric Haines' article in Glassner's ray tracing book (above) for more information, including treatment of special cases.

Another method is to sum the absolute angles from the point to all the vertices on the polygon. If the sum is 2 pi, the point is inside, if the sum is 0 the point is outside. However, this method is about an order of magnitude slower than the previous method because evaluating the trigonometric functions is usually quite costly.

Code for both methods (plus barycentric triangle testing) can be found in the Ray Tracing News, Vol. 5, No. 3, available from princeton.edu as /pub/Graphics/RTNews/RTNv5n3.Z.

This code has been updated and expanded. A long article on the topic appears in _Graphics Gems IV_ and the code (along with a timing test program) is available from princeton.edu as /pub/Graphics/GraphicsGems/GemsIV/GGemsIV.tar.Z.

How do I tessellate a sphere?

One simple way is to do recursive subdivision into triangles. The base of the recursion is an octahedron, and then each level divides each triangle into four smaller ones. Jon Leech <leech@cs.unc.edu> has posted a nice routine called sphere.c that generates the coordinates. It's available for FTP on ftp.ee.lbl.gov and princeton.edu.

How do I ray-trace height fields?

Height fields are a special case in ray-tracing. They have a number of uses, such as terrain rendering, and some optimization is possible. Thus, they get their own FAQ section. Note that further references can no doubt be located via the ray-tracing bibs in section 16 above.

The following paper seems to be the definitive reference: "Grid Tracing: Fast Ray Tracing For Height Fields", F. Kenton Musgrave, July, 1988.

This is available as "Research Report YALEU/DCS/RR-639" from Yale University, it's also in the SIGGRAPH '91 Fractal Modeling in 3D Computer Graphics and Imaging course notes, and (best of all) it's available on the net, at princeton.edu, as /pub/Graphics/Papers/musg88.ms.Z.

An implementation of this paper may be found in Rayshade.

Another paper exists: "Parametric Height Field Ray Tracing", D. W. Paglieroni, S. M. Peterson, Proceedings of Graphics Interface '92, Canadian Information Processing Society, Toronto, Ontario, May 1992, p. 192-200

And still one more: "The Synthesis and Rendering of Eroded Fractal Terrains", Musgrave, Kolb, Mace, Computer Graphics Vol 23, No. 3 (SIGGRAPH '89 Proceedings) p. 41-50

How do I find the area of a 3D polygon?

 The area of a triangle is given by (in C notation) 
     area = 0.5 * ( ( x[0] * y[1] ) + ( x[1] * y[2] ) + ( x[2] * y[0] ) -
	            ( x[1] * y[0] ) - ( x[2] * y[1] ) - ( x[0] * y[2] ) );

and the area of a planar polygon is given by 

     area = 0.0;

     for ( i = 0; i < n - 1; i++ )
         area += ( x[i] * y[i + 1] ) - ( x[i + 1] * y[i] );
     area += ( x[n - 1] * y[0] ) - ( x[0] * y[n - 1] );
     area /= 2.0;

or, equivalently but more quickly 

    area = 0.0;

    for ( i = 0; i < n - 1; i++ )
	area += ( x[i] - x[i + 1] ) * ( y[i + 1] + y[i] );
    area += ( x[n - 1] - x[0] ) * ( y[0] + y[n - 1] );
    area /= 2.0;

If the area is a negative number, the polygon or triangle is clockwise, if positive, it is counterclockwise.

From Ronald Goldman's Gem (in Graphics Gems II - see section 1 above), "Area of Planar Polygons and Volume of Polyhedra:"

The area of a polygon P0, P1, P2, ... Pn, not in the x-y plane, is given by 

     Area(Polygon) = 1/2 * | N . Sigma { Pk x Pk+1 } |

where N is the unit vector normal to the plane and P is a polygonal vertex. The . represents the dot product operator and the x represents the cross product operator. Sigma represents the summation operator. | | represents the absolute value operator. Pn+1 is equal to P0.

How do I convert between vector formats?

A lot of people ask about converting from HPGL to PostScript, or MacDraw to CGM, or whatever. It is important to understand that this is a very different problem from that addressed by the free image manipulation software below. Converting one image format to another is a fairly easy problem, since once you get past all the file header junk, a pixel is a pixel -- the basic objects are the same for all image formats. This is not so for vector formats. The basic objects -- circles, ellipses, drop-shadowed pattern-filled round-cornered rectangles, etc. -- vary from one format to another. Except in extremely restricted cases, it is simply not possible to do a one-to-one conversion between vector formats.

On the other hand, it is quite possible to do a close approximation, rendering an image from one format using the primitives from another. As far as I know, no one has put together a general toolkit of such converters, but two different HPGL to PostScript converters have been posted to comp.sources.misc. Check the index on your nearest archive site.

A related frequent question is how to convert from some vector format to a bitmapped image - from PostScript to Sun raster format, or HPGL to X11 bitmap. For example, some of the commercial PostScript clones for PC's allow you to render to a disk file as well as a printer. Also, the PostScript interpreters in the NeXT box and in Sun's X11/NeWs can be used to render to a file if you're clever. But in general, the answer is no. However, if someone were to put together a vector to vector conversion toolkit, adding a vector to raster converter would be trivial.

GNU ghostscript (from the FSF - current version 2.6.1) includes drivers for both ppm and gif format files, thus it can be used as a PostScript to ppm or a PostScript to GIF filter. (It implements essentially all of PostScript level 1 and alot of Display PostScript and level 2).

There is a package called hp2xx, which includes a fairly nice HP-GL previewer/converter, and which can convert to several formats, including PBM. The latest version is hp2xx-3.1.2.tar. It's available on many archive sites.

How do I get files if I can't ftp?

There are a number of sites that archive the Usenet sources newsgroups and make them available via an email query system. You send a message to an automated server saying something like "send comp.sources.unix/fbm", and a few hours or days later you get the file in the mail.

In addition, there is at least one FTP-by-mail server. Send mail to ftpmail@decwrl.dec.com saying "help" and it will tell you how to use it. Note that this service has at times been turned off due to abuse.

Where can I get ...

 This section provides information on how to obtain frequently sought items. I tend to shy away from commercial products other than books so as to remain as neutral as possible. I don't want to see things like "... the paint program recommended in the comp.graphics.misc FAQ!" get a toe-hold in my reality. :-)

Where can I get format documents for TIFF, IFF, GIF, etc.?

 You almost certainly don't need these due to the existence of a large quantity of very good free image manipulation software. Get one or more of these packages and look through them. Chances are excellent that the image converter you were going to write is already there.

But if you still want one of the format documents, many such files are available by anonymous ftp from the following sites:

There are many files in each of these directories. Your best bet is to go there and look around.

FITS stands for Flexible Image Transport System. It's a file format most often used in astronomy. Despite the name, it can contain not only images but other things as well. There is a regular monthly FITS basics and information posting on sci.astro.fits - read it if you want to know more.

Where can I get free image manipulation software?

There are a number of toolkits for converting from one image format to another, doing simple image manipulations such as size scaling, plus the above-mentioned 24 -> 8, color -> gray, gray -> b&w conversions.

While there is a full URL listed for many of these packages, this is really quite misleading. Most of these packages are available from numerouse sites. I highly recommend two things:

  1. Use archie or a similar tool to locate an ftp site close to you, rather than fighting the frothing hordes for access to wuarchive.
  2. ftp to your chosen site manually, change to the directory listed in the FAQ for your chosen package, and look around. You will often find newer versions or additional, related files.
That being said, here are the packages:

xv by John Bradley
X-based image display, manipulation, and format conversion package. XV displays many image formats and permits editing of GIF files, among others. The latest version is 3.10a, and may be found at John's site ftp.cis.upenn.edu as /pub/xv/xv-3.10a.tar.gz.

PBMPLUS by Jef Poskanzer
Comprehensive format conversion and image manipulation package. It is available at ftp.ee.lbl.gov as /pbmplus10dec91.tar.Z and at wuarchive.wustl.edu as /graphics/graphics/packages/pbmplus/pbmplus10dec91.tar.Z.

NETPBM
This is a Usenet community supported version of the PBMPLUS toolkit, including many new and updated converters. It is available at wuarchive.wustl.edu as /graphics/graphics/packages/NetPBM/netpbm-1mar1994.tar.gz. A mailing list exists as well.

IM Raster Toolkit by Alan Paeth (awpaeth@watcgl.uwaterloo.ca)
Provides a portable and efficient format and related toolkit. The format is versatile in supporting pixels of arbitrary channels, components, and bit precisions while allowing compression and machine byte-order independence. The kit contains more than 50 tools with extensive support of image manipulation, digital halftoning and format conversion. Previously distributed on tape c/o the University of Waterloo, an FTP version will appear someday.

Ed. Note: This is a very old blurb. Is this kit available on the net? If so, where? If not, how does one get it? Is it obsolete?

Utah RLE Toolkit
Conversion and manipulation package, similar to PBMPLUS. Available via FTP as cs.utah.edu:pub/urt-*, princeton.edu:pub/Graphics/urt-*, and freebie.engin.umich.edu:pub/urt-*.

Fuzzy Pixmap Manipulation by Michael Mauldin <mlm@nl.cs.cmu.edu>
Conversion and manipulation package, similar to PBMPLUS. Version 1.0 available via FTP at network.ucsd.edu as /graphics/fbm.tar.Z.

Xim (X Image Manipulator) by Philip R. Thompson
It does essential interactive image manipulations and uses x11r4 and the OSF/Motif toolkit for the interface. It supports images in 1, 8, 24 and 32 bit formats. Reads/writes and converts to/from GIF, xwd, xbm, tiff, rle, xim, and other formats. Writes level 2 postscript. Other utilities and image application library are included. Not a paint package. Available at gis.mit.edu as /pub/xim3i.tar.Z.

xloadimage by Jim Frost <madd@std.com>
Reads in images in various formats and displays them on an X11 screen. Available via FTP as in your nearest comp.sources.x archive.

xli, by Graeme Gill
This is an updated xloadimage with numerous improvements in both speed and in the number of formats supported. Available at ftp.x.org as /contrib/applications/xli.1.16.tar.gz.

TIFF Software by Sam Leffler <sam@okeeffe.berkeley.edu>
Nice portable library for reading and writing TIFF files, plus a few tools for manipulating them and reading other formats. Available via FTP as sgi.com:graphics/tiff/*.tar.Z.

xtiff
This is an X11 tool for viewing a TIFF file. It was written to handle as many different kinds of TIFF files as possible while remaining simple, portable and efficient. xtiff illustrates some common problems with building pixmaps and using different visual classes. It is distributed as part of Sam Leffler's libtiff package and it is also available on ftp.uu.net and comp.sources.x. xtiff 2.0 was announced in 4/91; it includes Xlib and Xt versions.

ALV
This is a Sun-specific image toolkit. Version 2.0.6 was posted to comp.sources.sun on 11dec89. Also available via email to alv-users-request@cs.bris.ac.uk.

popi
This is an image manipulation language. Version 2.1 posted to comp.sources.misc on 12dec89.

ImageMagick
This is an X11 package for display and interactive manipulation of images. Includes tools for image conversion, annotation, compositing, animation, and creating montages. ImageMagick can read and write many of the more popular image formats. Available from ftp.x.org as /contrib/applications/ImageMagick/ImageMagick-3.7.tar.gz.

Khoros
This is a huge (~100 meg) graphical development environment based on X11R4. Khoros components include a visual programming language, code generators for extending the visual language and adding new application packages to the system, an interactive user interface editor, an interactive image display package, an extensive library of image and signal processing routines, and 2D/3D plotting packages. Available at ftp.eece.unm.edu as /pub/khoros/*. A newsgroup exists for the discussion of khoros and khoros-related topics, comp.soft-sys.khoros.

LaboImage
This is a SunView-based image processing and analysis package. It includes more than 200 image manipulation, processing and measurement routines, on-line help, plus tools such as an image editor, a color table editor and several biomedical utilities. Available via anonymous FTP on nic.funet.fi in /pub/graphics/packages.

The San Diego Supercomputer Center Image Tools
These are software tools for reading, writing, and manipulating raster images. Binaries for some machines are available at sdsc.edu as /pub/sdsc/graphics/imtools/*.

Independent JPEG Group's free JPEG software
The Independent JPEG Group has written a package for reading and writing JPEG files. FTP to ftp.uu.net:graphics/jpeg/jpegsrc.v?.tar.gz

bit (Bitmap Image Touchup) by T.C. Zhao
This is a full color viewer/editor with a variety of features. SGI only. It may be obtained via FTP at monte.svec.uh.edu in /pub/bit.

"Libreria de Utilidades Graficas" or "Graphic Utilities Library"
This is a library of subroutines for image manipulation. It has routines for loading, viewing and manipulationg a variety of formats. It may be obtained at ftp.uniovi.es as /uniovi/mathdept/src/liblug.tar.gz.

Dore' (Dynamic Object Rendering Environment)
Dore' is a powerful 3D graphics subroutine library. It provides a comprehensive set of tools for creating graphics applications. It is also easy to use, portable, and extendable. This version has interfaces/drivers to X11, PEX, IrisGL, OpenGL, Postscript and more. It is known to run on NetBSD 1.0, Linux, FreeBSD, Solaris 2.3, and OSF/1. It has also been ported to Windows NT 3.5. The official distribution site is sunsite.unc.edu, where it may be found in pub/packages/development/graphics/Dore as pdore-6.0.tar.Z.

XMegaWave
XMegaWave is a graphics window environment oriented to image processing. It is based in the collaboration between researchers from the University of Balear Islands (U.I.B.), The University of Las Palmas (U.L.P.G.C.) and the University of Paris IX Dauphine (U.P.D.). XMW is oriented to UNIX workstations which work with X11R4 and Motif1.1 libraries (this XMW version). Currently, it is available for HP-Apollo and SGI workstations. Full source is not available as of yet, but the authors say they will cooperate in getting other versions built. XMW may be obtained on ftp.dis.ulpgc.es in the /investigacion/ami/XMegaWave directory.
Please do *not* post or mail messages saying "I can't FTP, could someone mail this to me?" There are a number of automated mail servers that will send you things like this in response to a message. Refer to the section of this document titled How do I get files if I can't ftp? for more help.

Also, the newsgroup alt.graphics.pixutils is specifically for discussion of software like this. You may find useful information there.

Where can I get free plotting software?

Gnuplot is a command-driven interactive data/function plotting program. It runs on just about any machine, and is very flexible in terms of supported output devices. The official North American distribution site for the latest version is dartmouth.edu in /pub/gnuplot. More information is available from the USENET newsgroup comp.graphics.gnuplot and its FAQ, graphics/gnuplot-faq.

ACE/gr (xmgr - Motif/xvgr - XView) is a data/function plotting tool for workstations or X-terminals using X. Available from ftp.teleport.com in /pub/users/pturner/acegr. There is also a WWW page for this package at http://www.teleport.com/~pturner/acegr/.

robotx (Robot) is a general purpose plotting and data analysis program. Requires XView, X-terminal or workstation. Available from ftp.x.org as /R5contrib/robotx0.48.tar.gz. There is a much improved version in beta testing as well. Contact corbet@bastet.gsfc.nasa.gov for info.

Xgraph is a popular two-dimensional plotting program that accepts data in a form similar to the unix program graph and displays line graphs, scatter plots, or bar charts on an X11 display. Available from a multitude of sites, including ftp.cs.umn.edu, as xgraph-11.3.2.tgz.

XGobi is an interactive dynamic graphics program for data visualization in the X Window System. It is especially designed for the exploration of multivariate data. It may be found at ftp.archie.au in /graphics/graphics/packages/XGobi.

XgPlot is a 3d plotting packages which supports linear, log, and probability scaling of axes, as well as division marker lines in the graph. It can plot up to 20 datasets on a single graph, and the graph may be saved to or loaded from an ascii graph description file. It may be found at ftp.x.org as /R5contrib/XgPlot-4.4.tar.Z.

PLOTMTV is a multipurpose X11 plotting program. It's capabilities include 2D line and scatter plots (x-vs-y), contour plots, 3D surface, line and scatter plots as well as vector plots. The program has an rough but functional Graphical User Interface, through which it is possible to zoom in, zoom out, pan, toggle between 2D and 3D plots, and rotate 3D plots. Both color and grayscale postscript output are supported. It may be found at ftp.x.org as /contrib/applications/Plotmtv1.4.1.tar.Z.

Where can I get standards documents?

The American National Standards Institute sells ANSI standards, and also ISO (international) standards. Their sales office is at 1-212-642-4900, mailing address is 1430 Broadway, NY NY 10018. It helps if you have the complete name and number.

Some useful numbers to know:

Language bindings are often separate but related numbers; for example, the GKS FORTRAN binding is X3.124.1-1985.

Standards-in-progress are made available at key milestones to solicit comments from the graphical public (this includes you!). ANSI can let you know where to order them; most are available from Global Engineering at 1-800-854-7179.

Where can I get 3D objects?

So far, I know of only one really large clump of them on the net. It is located at avalon.vislab.navy.mil. The site administrators request that major downloads be kept to non-peak hours. Their official mirror site is ftp.kpc.com.

Where can I get MRI and CT scan volume data?

Volume data sets are available from the University of North Carolina at omicron.cs.unc.edu (152.2.128.159) in /pub/softlab/CHVRTD. (Commercial use is prohibited.)

Where can I get MPSC and AOEGA info?

 The Motion Picture Screen Cartoonists and Affiliated Optical Electronic and Graphic Arts, Local 839 IATSE is pleased to announce the availability by anonymous FTP of information files about our organization.

Local 839 IATSE is the largest local union of motion picture graphic artists in the world. We have over 1,500 active members employed in animation and CGI in Southern California.

These files are available at ftp.netcom.com:/pub/mp/mpsc839 via anonymous ftp.

For further information, contact them at mpsc839@netcom.com.

Graphics-related Mailing Lists

 There are a variety of graphics-related mailing list out there, each covering either a single product or a single topic. I have been an active participant in several of these for some time now, and find the focus and expertise which can be brought to bear on an isolated topic to be nothing short of amazing.

Please send corrections if you notice outdated or erroneous information in this list! Also, feel free to send me any other lists you would like to see added.

Imagine mailing list

The Imagine mailing list provides a discussion forum for users of the Imagine 3D Rendering and Animation package from Impulse. Currently, Imagine runs on the Amiga and the PC.

To subscribe, send mail to imagine-request@email.sp.paramax.com with the word "subscribe" in the subject line.

DCTV mailing list

The DCTV mailing list provides a discussion forum for users of the Digital Creations DCTV box, software, and file formats. DCTV is an Amiga graphics module.

To subscribe, send mail to DCTV-request@nova.cc.purdue.edu with the word "subscribe" in the subject line.

Rayshade Users mailing list

The Rayshade Users mailing list provides a discussion forum for users of the Rayshade raytracer. Rayshade is a public domain raytracer, with source available on the net. It runs on most Unix boxes, as well as the Amiga, Mac and PC platforms. To subscribe, send mail to rayshade-request@cs.princeton.edu with the word "subscribe" in the subject line.

Lightwave mailing list

The Lightwave mailing list provides a discussion forum for users of the Lightwave 3D Rendering and Animation package from Newtek. Currently, Lightwave runs on the Amiga, but it will soon be available on various other platforms.

To subscribe, send mail to lightwave-request@bobsbox.rent.com with the "subscribe lightwave-l address" in your message.

Video Toaster mailing list

The Video Toaster mailing list provides a discussion forum for users of the Video Toaster product from Newtek. The Video Toaster is an Amiga board which includes Lightwave and a lot of video functionality.

To subscribe, send mail to toaster-request@bobsbox.rent.com with "subscribe toaster-l address" in your message.

Mailing List For Massive Parallel Rendering

This list title seems pretty self-explanatory. I believe it is primarly a Unix-oriented list.

To subscribe, send mail to mp-render-request@icase.edu with the word "subscribe" in the subject line.

Netpbm mailing list

The Netpbm mailing list provides a discussion forum for the net-supported netpbm package. I believe this to be largely a developer forum. Netpbm runs on just about any platform you could name.

To subscribe, send mail to oliver@fysik4.kth.se with the word "subscribe" in the subject line.

POV-Ray mailing list

The POV-Ray mailing list provides a discussion forum for users of the POV-Ray raytracer. POV-Ray is a public domain raytracer, with source available on the net. It runs on most Unix boxes, as well as the Amiga, Mac and PC platforms. To subscribe, send mail to listserv@vm3090.ege.edu.tr with "subscribe dkb-l" in the subject line.

RayDream mailing list

The Ray Dream mailing list provides a discussion forum for users of the Ray Dream Rendering and Animation package. Currently, Ray Dream runs only on the Mac.

To subscribe, send mail to listserv@cornell.edu with "subscribe raydream-l address" in your message.

Computational Geometry mailing list

The Computational Geometry mailing lists are meant for those working or interested in computational geometry. There are actually three separate but related lists:

To subscribe to one of these lists, send mail to compgeom-request@research.att.com with the message "subscribe xxxx" in the message body or subject line, where xxxx is the name of one of the three lists.

The compgeom list also provides some other neat stuff, such as a bibliographic search service. Send mail to compgeom-request@research.att.com with the message "send readme" for more information.

Photoshop mailing list

The Photoshop mailing list provides a discussion forum for users of the Photoshop image conversion and manipulation package from Adobe. Adobe Photoshop runs on Windows, Macintosh, and SGI platforms. The latest version, 3.0, does not work properly under OS/2 and Adobe refuses to address the problem (editorial comment).

To subscribe, send mail to photshop@bgu.edu with "subscribe" in the body of your message.

3DStudio mailing list

The 3dstudio mailing list provides a discussion forum for users of the 3D Studio modelling and rendering package from Autodesk. Autodesk 3D Studio runs only on the PC platform, AFAIK.

To subscribe, send mail to majordomo@autodesk.com with "Subscribe 3dstudio <address>" in the body of your message. The <address> section is optional, and should not include the <>.

KPT mailing list

The KPT mailing list provides a discussion forum for users of Kai's Power Tools, a set of cool texture plugins for Adobe Photoshop and other packages. Kai's Power Tools work on Windows and the Mac.

To subscribe, send mail to listserv@netcom.com with "subscribe kpt-list" in the body of your message.

KODAK Photo CD mailing list

The KODAK Photo CD mailing list is a public mailing list for discussion of the Photo CD format and related topics.

To subscribe, send mail to listserv@info.kodak.com with the command "SUBSCRIBE PHOTO-CD <first-name> <last-name>", substituting your own first and last names in the obvious spots. Both these names and the address you subscribe from will be used by the mailing list software.

Caligari TrueSpace mailing list

The Caligari mailing list provides a discussion forum for users of the Caligari TrueSpace Rendering and Animation package from Caligari. I believe Caligari currently runs on the Amiga and PC (Windows) platforms.

To subscribe, send mail to truespace-request@cs.uregina.ca with "subscribe" in your message.

Global Illumination mailing list

The Global Illumination mailing list is a forum for the discussion of research issues pertaining to the simulation of 'global illumination', that is the balance of radiant energy between a set of surfaces of radiatively active media. This is not a list for the newbie or the dabbler - 75% of the current members are researchers in academic environments.

To subscribe, send a message to globillum-request@imag.fr containing your name, affiliation, and 2 lines describing your interests. There is also an affiliated Global Illumination WWW page, http://safran.imag.fr/Membres/Francois.Sillion/globillum.html

Fractal Design Painter mailing list

The Fractal Design Painter mailing list provides a discussion forum for users of the Fractal Design Painter package. I believe Fractal Design Painter currently runs on the PC (Windows) and Mac platforms.

To subscribe, send the message "subscribe painter-list" to listserv@netcom.com.

SIGGRAPH

 SIGGRAPH, the Special Interest Group for Graphics of the Association for Computing Machinery, is the premiere professional organization in the computer graphics world. It is so active and so pervasive that I feel it deserves its own section.

SIGGRAPH information online

ACM-SIGGRAPH provides an online information site at siggraph.org (128.248.245.250). This site provides SIGGRAPH information via both anonymous ftp and an electronic mail archive server.

The anonymous ftp service is very standard, and the ftp directory includes both conference and publications subdirectories.

To retrieve information by electronic mail, send mail to archive-server@siggraph.org and in the subject or the body of the message include the message send followed by the topic and subtopic you wish. A good place to start is with the command send index which will give you an up-to-date list of available information.

The coolest way to get SIGGRAPH info, of course, is via their WWW page at http://www.siggraph.org.

How to join ACM/SIGGRAPH

Probably the easiest way to join ACM/SIGGRAPH is to trot over to your local technical library and find a copy of Communications of the ACM. Somewhere within the first few pages will be an application blank. Fill it out and mail it in. ACM membership for students costs $24.00, Voting or Associate Membership $79.00 (yearly).

SIGGRAPH student membership costs an additional $50.00, $59.00 for Voting or Associate Members (also yearly). To get TOG (Transactions on Graphics) it's another $27.00 for students and $32.00 for Voting or Associate Members (TOG is an ACM publication, not a SIGGRAPH publication).

If you just want to join SIGGRAPH without joining ACM, it'll cost you $85.00 (no student discount).

There are surcharges for overseas airmailing of publications.

ACM Member services may be contacted via email at acmhelp@acmvm.bitnet. Their phone number is (212) 626-0500. FAX number (212) 944-1318. Snailmail address ACM, PO Box 12114, Church Street Station, NY, NY 10257

SIGGRAPH `95 will be held in Los Angeles, California, August 6-11, 1995.

SIGGRAPH Online Bibliography Project

The ACM SIGGRAPH Online Bibliography Project is a database of over 15,000 unique computer graphics and computational geometry references in BibTeX format, available to the computer graphics community as a research and educational resource.

The database is located at "siggraph.org". Users may download the BibTeX files via FTP and peruse them offline, or telnet to "siggraph.org" and log in as "biblio" and interactively search the database for entries of interest, by keyword.

Web users may also access the SIGGRAPH Online Bibliography Project via the URL http://siggraph.org/library/bibliography/bibliography.html.

Additions/corrections/suggestions may be directed to the admin, "bibadmin@siggraph.org".

Check out John Grieggs' Home Page
grieggs@primenet.com