The RADIANCE Lighting Simulation and Rendering System

Gregory J. Ward /


1. Introduction

2. System Design Goals

2.1 Ensure Accurate Calculation of Luminance

2.2 Model Both Electric Light and Daylight

2.3 Support a Variety of Reflectance Models

2.4 Support Complicated Geometry

2.5 Take Unmodified Input from CAD Systems

3. Approach

3.1 Hybrid Deterministic/Stochastic Ray Tracing

3.2 Cached Indirect Irradiances for Diffuse Interreflection

3.3 Adaptive Sampling of Light Sources

3.4 Automatic Preprocessing of "Virtual" Light Sources

3.5 User-directed Preprocessing of "Secondary" Sources

3.6 Hierarchical Octrees for Spatial Subdivision

3.7 Patterns and Textures

3.8 Parallel Processing

3.9 Animation

3.10 Implementation Issues

4. Applications and Results

4.1 Electric Lighting

4.2 Daylighting

5. Conclusion

6. Acknowledgements

Most of the color figures in this paper represent the independent work of Radiance users, and are reprinted with permission. Figure 5 was created by Charles Ehrlich from a design by Mark Mack Architects of San Francisco. Figure 11 was created by Cindy Larson. Figures 12 and 13 were created by Martin Moeck of Siemens Lighting, Germany. Figure 14 was created by Steve Walker of Ove Arup and Partners, London. Figure 15 was created by Robert Shakespeare of the Theatre Computer Visualization Center at Indiana University. Figures 16, 18 and 19 were created by Scott Routen and Reuben McFarland of the University Architect's Office at Indiana University. Figures 17 and 20 were created by John Mardaljevic of the ECADAP Group at De Montfort University, Leicester.

The individuals who have contributed to Radiance through their support, suggestions, testing and enhancements are too numerous to mention. Nevertheless, I must offer my special thanks to: Peter Apian-Bennewitz, Paul Bourke, Raphael Compagnon, Simon Crone, Charles Ehrlich, Jon Hand, Paul Heckbert, Cindy Larson, Daniel Lucias, John Mardaljevic, Kevin Matthews, Don McLean, Georg Mischler, Holly Rushmeier, Jean-Louis Scartezzini, Jennifer Schuman, Veronika Summeraur, Philip Thompson, Ken Turkowski, and Florian Wenz.

Work on Radiance was sponsored by the Assistant Secretary for Conservation and Renewable Energy, Office of Building Technologies, Buildings Equipment Division of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. Additional funding was provided by the Swiss federal government as part of the LUMEN Project.

7. Software Availability

8. Bibliography

9. Appendix