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Photon-mapping in climate-based daylight modelling with high-resolution BSDFs

Publication Type:

Journal Article


Energy and Buildings, Volume 205 (2019)


BSDF, Climate-Based Daylight Modelling, complex fenestration, Five-Phase Method, photon mapping, radiance


Visual comfort assessments employing luminance-based metrics rely on efficient Climate-Based Daylight Modeling (CBDM) techniques for image synthesis. Data-driven Bidirectional Scattering Distribution Function (BSDF) models allow to isolate internal light paths in optically Complex Fenestration Systems (CFSs) from CBDM. Bidirectional photon mapping is proposed for the efficient sampling of such models in the calculation of the direct solar component in CBDM. The method allows accurate image synthesis for visual comfort assessments with only two calculation steps, achieving comparable accuracy as the established but complex Five Phase Method (5PM). The validity of the approach is confirmed by comparison with backward ray-tracing. Its exemplary application to compare two CFSs in terms of glare control demonstrates the importance to achieve reconcilability of conflicting targets such as view and glare control in daylighting.