Radiance 3.4 and Open Source Development
Greg Ward

Talk Overview
* Radiance Development History
* The Good
* The Bad and the Ugly
* Radiance 3.4
	* What is There
	* What is Missing
* Open Source Development

Radiance Development History
* First Official Release 1.0 in January 1989
* LBNL Releases through 3.1 in July 1997
* Code Split Three Ways:
	* LBNL MPI parallel rendering development
	* LBNL Desktop Radiance development
	* SGI Holodeck development
* New Release 3.4 in January 2002

The Good: 1 Primary Author
* Code consistency & reliability
* A feeling of responsibility
* An ultimate source for technical answers

The Good: Advanced Users
* Difficult but powerful software attracts talented users
* Talented users have good ideas
* Talented users have interesting problems 
* Interesting problems stress-test algorithms
* Some researchers even validate their simulations

The Good:  Rendering with Radiance
* Author wrote intro. and technical chapters
* Rob Shakespeare wrote tutorial chapters
* Other talented users wrote application chapters
	* Charles Ehrlich on Lighting Analysis
	* John Mardaljevic on Daylighting
	* Erich Phillips on Roadway Lighting
	* Peter Apian-Bennewitz on Animation

The Bad and the Ugly
* Being the primary author meant that when I left LBNL, development fragmented
* Code branches diverged even within LBNL
* Technical support also suffered
* Old-style C code was never updated
	(My excuse -- it still works!)
* Some code developments could be lost

Radiance 3.4: What is There
* Holodeck rendering system
* New and improved ray tracing utilities
	* vwrays and new rtrace options
* Bug fixes and improvements
	* glrad program for OpenGL rendering
	* xform -f option for faster scene generation
	* Increased max. scene complexity
	* New fonts (Verdana, Pix)
Note: Most bug fixes were included in patches to 3.1.

Radiance 3.4: What is Missing
* David Robertson's optimizations
* Hooks for compiled patterns in C
* Portability and readability improvements
* MPI support for parallel rendering
* Windows port and additions
* ximage and rview replacements

Open Source Development
* Open Source definition
* Open Source and Radiance
* How will this affect Radiance developers?
* How will this affect Radiance users?

Open Source Definition
* Free program distribution
* Must include original source code
* Must be free (or cost of distribution)
* Must allow redistribution and derivative work
* Permits restriction that derivatives be patched from authors' original source
* Adds "no discrimination" clauses
Notes:
Taken from the website "http://www.opensource.org/docs/definition.php".
The "no discrimination" clauses prohibit discrimination and
restriction of software use by persons or groups, or restrictions
on associated software use, or application areas.

Open Source and Radiance
* Until now, anyone wishing to redistribute any version of Radiance required a license
	* A two-year, renewable license cost $10000
	* Approximately 10 licenses were sold
* Beginning December 1, 2002, LBNL will make Radiance available as Open Source
* Code was always available -- now you may build on it and share your additions
Notes: 
The official LBNL announcement may be found at
"http://radsite.lbl.gov/radiance/announcement.html".
We will probably make a "patch requirement" to keep explicit what is
original and what is derived code.  Since this is a complex lighting
simulation system (not to mention a complex pile of C code),
the potential for introducing errors should never be underestimated.

How Will Open Source Affect Radiance Developers?
* In the past, developers had to offer their patches to Radiance source separately -- now, they can distribute complete package
* Companies wishing to capitalize on Radiance may do so without a license
* Code branching may be a problem
Note: LBNL will not endorse or guarantee any derivative of Radiance. 
This should not be a surprise, since it never endorsed any version
of Radiance in the first place.

How Will Open Source Affect Radiance Users?
* New versions may have new capabilities
* New products may become available
* New sources of technical expertise
* Questions may arise as to simulation integrity

The Future Is Yours
* The future of Radiance depends on interested users and developers
* I will continue to be involved and available for consultation at some level
* Much of the work is in derivative software applications that utilize Radiance core lighting & daylighting simulation engine