Reverse radiance: a fast accurate method for determining luminance

Kenneth E. Moore; Ronald F. Rykowski; Sanjay Gangadhara

doi:10.1117/12.931491

11 October 2012 Reverse radiance: a fast accurate method for determining luminance

Kenneth E. Moore, Ronald F. Rykowski, Sanjay Gangadhara

Proceedings Volume 8485, Nonimaging Optics: Efficient Design for Illumination and Solar Concentration IX; 84850I (2012) https://doi.org/10.1117/12.931491
Event: SPIE Optical Engineering + Applications, 2012, San Diego, California, United States

Abstract

Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

Citation Download Citation

Kenneth E. Moore, Ronald F. Rykowski, and Sanjay Gangadhara "Reverse radiance: a fast accurate method for determining luminance", Proc. SPIE 8485, Nonimaging Optics: Efficient Design for Illumination and Solar Concentration IX, 84850I (11 October 2012); https://doi.org/10.1117/12.931491

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