Graphics Muse

"Linux Gazette...making Linux just a little more fun! "

Welcom to the Graphics Muse
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© 1996 by mjh

Button Bar muse:
  1. v; to become absorbed in thought
  2. n; [ fr. Any of the nine sister goddesses of learning and the arts in Greek Mythology ]: a source of inspiration
Welcome to the Graphics Muse! Why a "muse"? Well, except for the sisters aspect, the above definitions are pretty much the way I'd describe my own interest in computer graphics: it keeps me deep in thought and it is a daily source of inspiration.

[Graphics Mews] [Musings] [Resources]
indent This column is dedicated to the use, creation, distribution, and dissussion of computer graphics tools for Linux systems.
      Last month I introduced a new format to this column. The response was mixed, but generally positive. I'm still getting more comments on the format of the column rather than the content. I don't know if this means I'm covering all the issues people want to hear about or people just aren't reading the column. Gads. I hope it's not the latter.
      This month's issue will include another book review, a discussion on adding fonts to your system, a Gimp user's story, and a review of the AC3D modeller. The holiday season is always busy one for me. I would have liked to do a little more, but there just never seems to be enough time in the day.
Graphics Mews

      Disclaimer: Before I get too far into this I should note that any of the news items I post in this section are just that - news. Either I happened to run across them via some mailing list I was on, via some Usenet newsgroup, or via email from someone. I'm not necessarily endorsing these products (some of which may be commercial), I'm just letting you know I'd heard about them in the past month.
      I went wondering through a local computer book store this month and scanned the graphics texts section. I found a few new tidbits that might be of interest to some of you.      

3D Graphic File Formats: A Programmers Reference

      Keith Rule has written a new book on 3D Graphics File Formats. The book, which contains over 500 pages, has been published by Addison-Wesley Developers Press and is listed at $39.95. It includes a CD-ROM with a software library for processing various 3D file formats (both reading and writing), but the code is written for MS systems. Keith states there isn't any reason why the code shouldn't be portable to other platforms such as Linux. Any takers out there?
ISBN 0-201-48835-3
indent indent

OpenGL Programming for the X Window System

      I noticed a new text on the shelf of a local book store (Softpro, in Englewood, Colorado) this past month - Mark J. Kilgard's OpenGL Programming for the X Window System. This book, from Addison Wesley Developers Press, appears to have a very good coverage of how to write OpenGL applications that make use of X Windows API's. I haven't read it yet (or even purchased it - yet, but I will) so can't say how good it is. Mark is the author of the GLUT toolkit for OpenGL. GLUT is to OpenGL what Xt or Motif is to Xlib. Well, sort of.

Fast Algorithms for 3D-Graphics

      This book, by Georg Glaeser and published by Springer, includes a 3.5" diskette of source for Unix systems. The diskette, however, is DOS formatted. All the algorithms in the text are written using pseudocode, so readers could convert the algorithms to the language of choice.
indent indent

ImageMagick 3.7.8 released, including a new set of image library plug-ins

      A new release of ImageMagick has been released from Alexander Zimmermann. This release includes a "Plug In" library containing the various image libraries ImageMagick needs to run. Alexander has uploaded this new release to Sunsite as well as ImageMagick's Web site.

MpegTV Player v0.9

      A new version of the MpegTV Player has been released. This version now includes audio support.
indent indent

Imaging Technology Inc. IC-PCI frame grabber board driver

      The second public release (v 0.2.0) of a kernel module for the Imaging Technology Inc. IC-PCI frame grabber board (rev 1) and the AM-VS acquisition module has been released. This driver is maintained by GOM mbH (Gesellschaft fuer optische Messtechnik) TU Braunschweig, Institute for Experimental Mechanics. A full motion video test program and a read function for original camera files are included.
Author: Matthias Stein
Maintained by: Dirk Bergmann
This software is not really free (see the LICENSE file).

Viewmol 2.0 released

      I don't know much about this tool, but it appears to have alot of graphics related features, so I thought I'd mention it here. The LSM gives the following information:

Viewmol is a program for the visualization of outputs from quantum chemical as well as from molecular mechanics programs. Currently supported are Gaussian 9x, Discover, DMol/DSolid, Gulp, Turbomole, and PDB files. Properties visualized include geometry (with various drawing modes), vibrations (animated or with arrows), optimization history/MD trajectories, MO energy level diagram, MOs, basis functions, electron density. Drawings can be saves as TIFF, HPGL, Postscript, input files for Rayshade.


Did You Know?

      3D Site ( is a Web site devoted to everything 3D. There are job postings, links to free repositories of 3D models and lots of other valuable information.

      3D Cafe ( is another Web site with various useful 3D information. It also maintains a large collection of DXF and 3DS model files.

An Important Survey

      I've been talking to a couple of publishers about doing a book aimed at Linux users. I'd like to write a User's Guide for the Gimp but the publisher feels a more general text on doing Web-based graphics might have a wider appeal (face it - the Linux audience just isn't the size of the MS audience - yet - but the publishers are considering both types of books). I told them I'd ask my readers which type of text they'd like to see. The Gimp book would include details on how to use each of the applications features as well as a number of tutorials for doing various types of effects. The book on doing graphics for Web pages would include discussions on using HTML, information on tools besides the Gimp and a few case studies (including something on animation). However, the Web book wouldn't go into as much detail for each of the tools. That information would be more general in nature.
      I don't have a server to run any CGI scripts to register votes, so simply mail me with your opinions. Thanks!

A Call for Help

      I plan on covering more 3D tools in the future, but I have to learn to use them first. The next tool I'm going to look into is BMRT. If you use BMRT and want to help me get started drop me a line. I'd like to do an introduction to BMRT in the March issue if possible but I want to make sure I know what I'm talking about first. Thanks!



A Gimp User's Story (or "Why I Use the Gimp")

The following piece was posted on the Gimp User's Mailing list by Mike Phillips.

      At work, we have a "Library News Network", which is actually a 386 pc running a TV via a video converter in a continual slideshow with information about upcoming events in the law library and the law school. Last year, my boss did some stuff in Freelance Graphics which, quite frankly, was rather limited in effect.
      This year, it's my baby, and I'm making the slideshow (640x480x256 GIF files, run by a simple DOS program and looped by a batch file) in the GIMP. Here are some things I've done to make the text more readable and make the display reasonably eye-catching. Nothing fancy, but hopefully the tricks will give other people ideas to play with on their own.
      First, don't use a plain background. The blend tool is very nice for this, and shaded green or blue with bright text is rather nice looking. Start with a color and add some noise Create a blend image of the same size and multiply by the image with noise. This creates a very cool background for a slide. Better yet, if there's an appropriate photograph, use it! (I used a gorgeous picture of Yosemite Park to announce an environmental law symposium, and a decent photo of the U.S. Supreme Court justices to announce our Supreme Court Preview.)
      On the subjects of backgrounds, since I don't remember seeing this tip, here's a quickie for clouds: Make a plasma of the appropriate size, grayscale it, convert it back to color, and Brightness/Contrast/Gamma it into submission. I usually knock the brightness up about 75-100, and the blue up to around 5 and the green to about 2. Instant pretty sky (Obviously, skies from other planets could be done with reds and greens and whatnot.)
      For the text, nothing beats some good fonts. Hit a font archive, or buy a $10-$15 CD filled with fonts. Granted, I have the Caldera Network Desktop, so I can use some fonts that (I think) XFree can't, thanks to the font server, but it's worth a shot. I got a CD with 1250 fonts for $13. [Ed. Next month I'll cover how to add fonts to your system so you can use them with the Gimp. mjh]
      Here's a variation on the rounded-text tips: work out your text, then Duplicate it once and Offset it once (say 4x4). Edge Detect then Invert the duplicate and Gaussian Blur the offset twice. Multiply the resulting images, and use the original as a mask to composite something else over the image resulting from the multiplication. Very nice, edged & floating/shadowed text. Shows up great on a TV monitor.
      For the text, use any appropriate single color. Bright colors and high contrast work very well for what I do, although I've played with textures, rippled blends, plasma clouds, and what-not.
      Of course, it can be spiced up with all sorts of clipart (I heartily recommend Barry's Clipart Server (, from which I shamelessly borrow, and voila, instant slideshow!
      I have left our Fall Break edition of the LNN at: if you want to see some of what can be done with it. You might be better off watching the show when the graphics aren't resized to 320x240. Also, the latest version of these is available at

[Ed. Later Mike posted another message that included some interesting effects. I thought it might be appropriate to include them with his other posting.]

      Recently, while wandering through the plug-ins available, I found the charcoal plug-in. Compiled it, added it, used it. Rather nifty, actually. However, it got me thinking and experimenting, and I produced two potentially interesting effects:

(1) Pastel sketch: Take a color (RGB) image, Edge-detect it, Invert, and (optionally) contrast autostretch. On many images, this will produce a nifty pastel sketch. If the image is too high of detail, degrade the color or pixelize it first, otherwise you may end up with too many extraneous lines.

(2) Watercolor sketch: Take a color (RGB) image, make a grayscale of it. Edge Detect the grayscale (this will give you the sketch lines); this can be hard to balance the way you want, so you may want to threshold it or pixelize the image first. Then, pixelize and degrade the main image to 32 colors (16 or 20 works even better). Eliminate the background you don't want, Gaussian blur it a few times, and brighten it some. Multiply the edging onto it. Voila; (nearly) instant watercolor, akin to the court sketches on news shows.

Mike Phillips,


Jim Blinn's Corner - A Trip Down the Graphics Pipeline

indent I am not formally trained in computer graphics (1). Everything I know I've learned in the last year or so by reading, examining source code, and through the kind assistance of many members of the Net. So my ability to understand some of the more formal texts on computer graphics is limited.
      Given this limitation, I found I was still able to read and comprehend a good portion of Jim Blinn's book Jim Blinn's Corner - A Trip Down the Graphics Pipeline, which is a collection of articles taken from his column in the IEEE Computer Graphics and Applications journal. This book is the first of what may be two books, assuming there is sufficient interest in the first book. The second will cover a set of pixel arithmetic articles taken from the same column.
      In the preface Jim describes how he used a writing style that is "certainly lighter than a typical SIGGRAPH paper, both in depth and in attitude." I can't agree more. Computer graphics should be a fun subject and, despite the math, this book does provide a giggle here and there.
      Don't get me wrong, though. There is plenty of the technical details on how to compute positions in 3D space, perspective shadows, and subpixelic particles. Hefty stuff for the beginner. Nearly incomprehensible to the person who hasn't used matrix arithmetic in the past 8 years. Still, chapters like The Ultimate Design Tool (which talks about how an idea should start), and Farewell to Fortran (which talks about using various languages in computer graphics) provided enough non-mathematical discussions to let my brain recover while still keeping my interest peaked.
      I haven't read the book front to back yet. I'm saving whats left (about half the book) for my 16 days of freedom scheduled to start later this month. Its first on my reading list. Second will be my college Linear Algebra text. The first half of Jim's book reminded me about how much I'd forgotten in 8 years. Like the saying goes, one must strive for the impossible before they know what is possible.
indent indent indent

The IRTC - A raytracing competition for the fun of it

indent For the past few months, I've been helping to administer an Internet-based competition for users of raytracing software. This competition, the Internet Ray Tracing Competition or IRTC, is open to anyone interested in creating 3D images using software on any platform as long as the software falls within a few basic guidelines. It is based on another competition started back in 1994 by Matt Kruse. Matt eventually had to close down the contest due to the enormous amount of time it takes to run such a contest. At the time, he was more or less doing all the work himself.
      Earlier this year Chip Richards started to organize the contest once again. A group of interested individuals signed up to help out. In the end, most of us (myself included) provide only organizational input - ideas for rules or input on rulings regarding cheating (yes, there has been some of that), helping to select topics, and so forth. Most of the real work has been done by Chip, Bill Marrs, and Jon Peterson (although Jon has since had to move on to other things).
      The contest is made up independent rounds that last 2 months. Each round has a topic which entrants must use as the basis for their images. Entries are supposed to be new images, created during the span of the contest, however most people use bits and pieces of older models that they or someone else has created. The tools allowed vary but raytracing tools are preferred and no post processing is allowed (for example, you can't add a lens flare after the image has been rendered). Anyone is allowed to vote (currently) on the images and winners receive small prizes like CDs and prints of their images.

more IRTC... (same page as AC3D review)


The following links are just starting points for finding more information about computer graphics and multimedia in general for Linux systems. If you have some application specific information for me, I'll add them to my other pages or you can contact the maintainer of some other web site. I'll consider adding other general references here, but application or site specific information needs to go into one of the following general references and not listed here.

Linux Graphics mini-Howto
Unix Graphics Utilities
Linux Multimedia Page

Future Directions

Next month:
Let me know what you'd like to hear about!

  1. Anyone having an extra, unclaimed scholarship in computer graphics is encouraged to contact me. I give preference to those who have them within commuting distance of Denver, where I live.

Previous ``Graphics Muse'' Columns

Graphics Muse #1, November 1996
Graphics Muse #2, December 1996

Copyright © 1997, Michael J. Hammel
Published in Issue 13 of the Linux Gazette