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CIE 171:2006 Test Cases to Assess the Accuracy of Lighting Computer Programs: Results for AGi32 Version 1.94

Addendum: Analysis of Test Case 5.14

Independently performed by Dau Design & Consulting, Calgary, Alberta, Canada, this is an extensive compilation of test results performed per the publication CIE 171:2006, assembled on the recommendations of CIE Committee TC3.33

Buy the CIE 171:2006 publication

Articles, Presentations & Publications

SOFTWARE & COMPUTING: LIGHTING DESIGN: Colored light sources place new demands on lighting design software

By Ian Ashdown, FIES - Lighting Analysts, Inc.

The Influence of Interreflections on Color Perception

By Ian Ashdown, FIES - Lighting Analysts, Inc.

The Customer Is Always Right
(The Future of OLED lighting)
“Even with all the chatter surrounding OLEDs, proponents are well-advised to remember this simple maxim: people buy luminaires, not technology.” By Ian Ashdown and Brent York in the March 2010 issue of LD+A (

EULUMDAT and Absolute Photometry
PDF document
Press release

The joint agreement between Lighting Analysts, DIAL GmbH and byHeart Consultants for support of absolute photometry in the EULUMDAT photometric format.

THE APPLICATION OF PSEUDOCOLOR ANALYSIS TO ASSESS THE OBTRUSIVE LIGHT PRODUCED BY OUTDOOR LIGHTING INSTALLATIONS By José Luiz Pimenta, Sao Paulo, Brazil with assistance from David Speer of LAI for the 26th Session of the CIE in Beijing, China. An illustration of the value of Pseudocolor analysis in the evaluation of obtrusive outdoor lighting.

Accurate Modeling of LED Colors: A Scientific Approach By Ian Ashdown, P. Eng., LC, FIES in LEDs Magazine, October 2005 ( regarding specifying RGB colors for LED luminaires to compensate for poor color rendering by computer monitors.

Supplement to above for direct application to AGi32 Scaling method to correct SRE numbers in AGi32

Radiosity: A Programmer's Prospective By Ian Ashdown, P. Eng., LC, FIES (1994) is a 500-page undergraduate-level textbook on the mathematics of synthesizing photorealistic images using radiosity methods. It includes C++ source code for a fully-functional radiosity renderer that runs under MS-Windows. Out of print since 1998, the book is now available free (as in beer).

Thinking Photometrically II On May 29, 2001, byHeart Consultants CTO Ian Ashdown presented the "Thinking Photometrically II" workshop at Lightfair International in Las Vegas, NV. The objectives of this three-hour workshop were:
  1. An in-depth understanding of photometric reports, including IESNA LM-63, CIBSE TM-14, and EULUMDAT file formats.
  2. An explanation of the photometric measurement process and its relation to the accuracy and reliability of photometric reports.
  3. A non-technical analysis of lighting design software algorithms, with particular emphasis on understanding how they work and how to use them properly to produce photometrically accurate predictions and physically correct renderings.

The 46-page handout from this workshop is available here.

Modeling of Daylight for Interior Environments Presented by Ian Ashdown, P. Eng., LC, FIES at the IESANZ 2004 conference in Broadbeach, Australia

Research Papers

Eigenvector Radiosity Ashdown, I 2001 : MSc thesis, Department of Computer Science, University of British Columbia
Radiative Transfer Networks Revisited Ashdown, I 2002 : Journal of the illuminating Engineering Society 30(2):38-51 (Summer)
Eigenvector Radiosity - Corrigendum Ashdown, I 2003
SVD Radiosity Ashdown, I 2008

White Papers/Pages

Absolute Photometry, SSL & AGi32  
Primer on Photometric integrity from LTI Optics  
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