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An out-of-core photon mapping approach to daylight coefficients

TitleAn out-of-core photon mapping approach to daylight coefficients
Publication TypeJournal Article
Year of Publication2016
AuthorsSchregle R, Grobe LO, Wittkopf S
JournalJournal of Building Performance Simulation
Date Published05/2016
Keywordscache, daylight simulation, Morton code, out-of-core, paging, photon map

Climate-based daylight modelling (CBDM) is an effective means of assessing the performance of daylight redirecting components (DRCs) with highly directional scattering to determine their impact on daylight availability and visual comfort. Such a simulation imposes significant computational demands on commodity hardware as it requires high density luminance samples obtained by forward raytracing. We propose an out-of-core photon mapping method within the Radiance framework to compute high quality daylight coefficients as a basis for CBDM. The method is particularly suited to angularly selective DRCs exhibiting strong redirection in conjunction with non-uniform sky luminance distributions with high resolution subdivisions. Our implementation is a work in progress and currently accommodates up to 4.3G photons on disk, while optimizing the in-core memory footprint by loading only photons which actually contribute flux to sensor points. We also leverage the fact that photon paths are independent through parallelization.

Refereed DesignationRefereed