On spectral ray files of light sources using principal component analysis

Valéry Ann Jacobs, Sven Leyre, Jan Audenaert, Guy Durinck, Patrick Rombauts, Peter Hanselaer

Research output: Chapter in Book/Report/Conference proceedingConference paperResearch


To obtain realistic results in lighting simulation software, accurate models of light sources are needed. The advent of new light sources with spatial and angular color variations necessitates the addition of spectral information about the source. Including this information in the model of a light source, allows for spectral irradiance maps to be calculated and colorimetric information to be derived. Existing methods to include spectral information about the source require a large set of ray-files to be traced: for each wavelength step in the spectral range, a ray-file should be subsequently traced. Thereafter, the spectral irradiance map can be calculated at an arbitrary surface. Principal component analysis (PCA) allows us to characterize the angular variation of the spectral irradiance by a linear combination of parameters and base functions. Another possibility would be to construct “PCA ray files”, all of them exact copies of the photometric ray-file, yet four times replacing the luminous flux of each ray-file by a parameter resulting from the PCA. Assuming that only spectrally neutral materials are introduced between the source and the detection area, subsequent ray-tracing of these PCA ray files, allows their distribution to be determined on any task area. From this information, the absolute spectral irradiance at any point and in any direction can be constructed using a limited number of additional simulations. Whenever spectral information is desired at a task area, the proposed method allows for a fast and efficient way to improve the accuracy of simulations using ray-tracing.
Original languageEnglish
Title of host publication28th CIE SESSION
PublisherCIE Central Bureau Vienna-A
Number of pages6
ISBN (Print)9783902842558
Publication statusPublished - 1 Jul 2015
Event28th Session of the CIE - Manchester, United Kingdom
Duration: 28 Jun 20154 Jul 2015

Publication series



Conference28th Session of the CIE
Country/TerritoryUnited Kingdom

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