A field report on the Inaugural RADIANCE Workshop

A field report on the Inaugural RADIANCE Workshop

By Rob Guglielmetti (rpg@rumblestrip.org - www.rumblestrip.org)

Rob Guglielmetti is an architectural lighting designer specializing in the application of computer technology to the task of lighting design. He is the Director of Information Technology and head of lighting simulation programming and analysis at Renfro Design Group, Inc, an architectural lighting design firm in New York City NY, USA.

A field report on the Inaugural RADIANCE Workshop
University of Applied Sciences of Western Switzerland
(Ecole d'ingénieurs et d'architectes de Fribourg)
Fribourg, Switzerland Sept 30-Oct 1, 2002

In a world crowded with trade shows, computer fairs, and glitzy product launches, a quiet meeting was held in a quiet city in the middle of Switzerland. The topic of discussion was the computer graphics application called Radiance, and the collective enthusiasm, intellect, and ingenuity displayed by the 39 participants easily surpassed the buzz of any shindig that the folks from Autodesk could hope for.

Perhaps long overdue, this workshop was organized by Radiance author Greg Ward and Dr. Raphael Compagnon, a teacher at the University of Applied Sciences of Western Switzerland (which was the site of the workshop). Over the years Radiance has cultivated a relatively small but loyal following, composed of students, researchers, and designers scattered all over the globe. A moderately active mailing list provides the primary means of support for the product, and as a result Radiance users belong to a strange fraternity of friends whose primary means of identification is an email address. This workshop provided an opportunity for these people to associate some faces with those many email addresses, in addition to providing a forum for exhibiting the many ways this piece of software is being applied to the task of accurate lighting simulation.


Copyright Andrew McNeill / ArupLighting


Being the first of hopefully many of these events, a clear format or curriculum was probably difficult to arrive at. In the end, over twenty individuals volunteered to be speakers. The presentations were varied, and included topics like new products that either extend the functionality of Radiance or make Radiance more user friendly; examples of the use of Radiance in the visualization and lighting design fields; and experimental modifications and extensions to the the actual code itself. None of the presentations were hands-on tutorial style, but as a novice user of Radiance I still considered it a learning experience. If not for anything else, it was an inspiring view at the wealth of ways the Radiance calculation/rendering engine can be applied to the creation of better designs.

The recent announcement that Radiance will go open source was, unfortunately, not really clarified further at the workshop. The current situation of a December 1, 2002 date for making Radiance open source still stands; what that *means* still remains a mystery. The room was filled with interested parties, and you can be sure that for every interested set of ears in that room there are probably twenty or thirty other sets that are waiting with baited breath for the developments. Discussion of modernizing the code base was the order of the day. Radiance is based on K&R C, eschewing the use of prototypes. Today's programmers apparently are not well-versed in this programming paradigm, so extending the Radiance source has become the domain of a very specialized subset of interested parties in the computer graphics community. An effort to "ANSI-fy" the code is the primary directive, as well as reigning in the divergent development paths of Radiance and the more recent "Desktop Radiance" project. The hope is to be able to provide developers with a modern code base that allows for easy hooks
into the Radiance calculation engine.
 

Copyright 2002 Benjamin Black

Several individuals and firms presented their application of Radiance in daylighting design. I believe the heavy draw of serious lighting engineers to Radiance indicates the power and sophistication of this application. The prediction of the behavior of light on a space is so fantastically complex, it's no wonder that most software applications fall short of realistically dealing with all the variables. The forward thinkers of computerized daylighting simulation inevitably arrive at Radiance's doorsetp, and the presentations indicated that with careful application of Radiance and creative application of computer scripting techniques it is possible to analyze architectural daylighting problems in an efficient manner, virtually.

All workshop attendees received a CD-ROM containing the materials presented; this included renderings, source code, and papers. It's a valuable addition to any Radiance-phile's collection. Fortunately, the attendees agreed that it should become part of the public domain, and Peter Appian-Bennewitz has already hosted the materials (including an ISO image of the CD) on the Radiance website at:

http://www.radiance-online.org/radiance-workshop1/cd/

By now some of you are still perhaps wondering exactly what Radiance is. You may have stumbled upon this article as a visualization artist, maybe a regular visitor to CGArchitect, and clicked the link to this story. Maybe you use Viz, or Maya, or even the new Brazil release, and have been happily creating convincing renderings of natural & artificially illuminated scenes, and been impressed with the capability of current popular software applications. Many of these applications claim to be "physically-based", to boot. But Radiance is the only
application in existence today that can truly claim to be king of the hill in terms of realistic, physically-based, rendering and calculation lighting software. Based on a light-backwards ray tracing algorithm, Radiance is able to simulate a vast array of photometric phenomena, and the Radiance Workshop even introduced a new photon map module that further extends the functionality of the software. If you are new to Radiance, I suggest you visit the Radiance website(s) quoted in this article, and learn more about it.
 

Copyright 2002 Carsten Bauer

While long maligned for its lack of a GUI and its difficult learning curve, Radiance remains the greatest attempt to simulate the sometimes fleeting whims of photons with computer code. The workshop in Fribourg indicated that many individuals feel the same way, and are hard at work putting Radiance to that task. Several presentations also illustrated that people are aware of the difficulties of using Radiance, and applications and plug-ins are being developed that utilize the Radiance engine behind a more friendly GUI.

For additional information on Radiance, visit the following websites:

http://radsite.lbl.gov/radiance/HOME.html
http://www.radiance-online.org/

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