Second Annual Radiance Workshop Report

Second Annual Radiance Workshop Report - Lawrence Berkeley National Laboratories -- Berkeley, CA USA

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.


Last week I went to Berkeley, CA and had my mind expanded. It's not like you think.

Following the success of last year's first-ever International Radiance Workshop in Fribourg, Switzerland, the organizers decided to do it all over again. The second annual Radiance workshop -- a gathering of Radiance users from across the globe -- was reasonably well attended with about thirty peole showing up from all points around the world. They came to exchange ideas, share code, tell jokes, and basically geek out with Radiance. Lawrence Berkeley National Laboratories, Greg Ward and Judy Lai played hosts, and for a week in September my mind was filled with exciting new ways to use Radiance. Many of the attendees were meeting face to face for the first time, despite knowing each other quite well through the radiance-online.org mailing list, which has become the main means of technical support for Radiance users. The Radiance Workshop is equal parts meeting, reunion, seminar, support group and party.

For the uninitiated, Radiance is a physically-based, light-backwards raytracing software program capable of rendering scenes of fantastic complexity and realism. The software has been around for over a decade, but it seems to be used by a small niche of users -- primarily researchers and engineers -- perhaps due to its somewhat obtuse user interface. Radiance's UNIX-based suite of tools recently became open source software and there has been a flurry of activity on the user side as well as the development side. It's an exciting time for the Radiance community.

The workshop was expanded this year to include a tutorial component. If you've ever tried to use Radiance you know that live instruction from Radiance's author and other power users is very much worth the price of admission! The first three days of the event comprised the tutorials; Dr. John Mardaljavec was the primary instructor, giving the attendees a gentle introduction to the basics of Radiance, and progressing through to some daylighting applications of Radiance, material definitions, and walked us through a shell scripting example of animating the movement of the sun over the course of a day. There was an overlapping seminar on the first day, where Greg Ward (the program's author) and Georg Mischler (an active developer of Radiance and Radiance applications) illustrated the use of some of the new features of the latest version of Radiance, such as the new mesh primitive and the Holodeck ray cache, a very interesting step toward the ideal of physically accurate virtual reality.

Thursday dawned with the start of the "workshop talks", where attendees got a chance to address the audience and show off the work they are doing with Radiance. The presentations illustrated the wide range of possible applications for Radiance as well as the collective brilliance & enthusiasm that embodies the Radiance user community. There were presentations on using Radiance for daylighting design, parametric skylight design studies, and even physically accurate archaeological reconstructions.



Archaeological reconstruction Image credit: Veronica Sundstedt and Patrick Ledda; University of Bristol

Some other visual treats presented at the workshop included Greg Ward's HDR image viewer, which uses a set of transparencies -- one "sharp with color" and one "fuzzy in greyscale" -- placed in front of a couple of 50 Watt MR-16 lamps, which one views through a set of wide angle lenses to experience a scene of much greater dynamic range than possible with print or video monitors (try 10,000:1). The slides were produced with Radiance, which I think illustrates the capability and flexibility of the software as well as anything. Greg Ward also demonstrated his Photosphere application, which is an OS X-based image browser application. Created by Radiance's author, you'd expect an extra layer of physically-based functionality, and you won't be disappointed. Photosphere can create HDR images (similar to Paul Debevec's HDR Shop), but there are also some nice utilities for aligning the multiple exposures, and automatically figuring out your camera's response curve. If you are interested in trying Photosphere for yourself, have a look at www.anyhere.com.

All attendees received a CD-ROM containing all the presentation materials, and -- as it was last year -- the contents of that CD are available for download at www.radiance-online.org.



Daylight glare analysisImage credit: Andrew Bissell, copyright Buro HappoldÕs LiT

All too quickly, the week passed us by, but a lot of lessons were learned in those five days. Friendships were forged, and renewed; Radiance features were explained, code was copied, techniques traded. It truly was a mind expanding experience. Radiance is a monster to learn, the learning curve is Everest-like. But once you start using it, it begins to take on a life of its own. The depth of the software -- its seemingly limitless capability -- is daunting at first. The initial thought is "I'll never learn all this stuff". But what happens is that you end up seeing the myriad command line switches & arcane utilities as capabilities -- as opportunities -- rather than simply a bunch of confusing switches you have to understand, and that's when things get really exciting.

Hopefully there will another workshop next year; I have a lot to learn yet, and I learn a whole lot at these workshops. Maybe I'll see you there?


Some of the folks from the tutorial sessions Image credit: Greg Ward

Resources:

http://radsite.lbl.gov (Official Radiance website)
http://www.radiance-online.org (Radiance support site, with mailing lists & Workshop downloads)
http://www.lbl.gov (2003 Workshop hosts, Lawrence Berkeley National Laboratories)
http://www.anyhere.com (Greg Ward's software company; purveyors of Photosphere)
http://www.anyhere.com/gward/papers/pics2002.pdf (Paper describing Greg Ward's HDR image viewer)

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