Photon mapping to accelerate daylight simulation with high-resolution, data-driven fenestration models

Swiss Federal Office of Energy
International Conference on Climate Resilient Cities - Energy Efficiency and Renewables in the Digital Era 2019, CISBAT 2019 -- 4 September 2019 through 6 September 2019 -- -- 155202
Data-driven modelling provides a general means to represent optically complex fenestration in daylight simulation by its Bidirectional Scattering Distribution Function (BSDF). Radiance employs the tensor tree as a compact data structure to store the BSDF at high directional resolution. The application of such models under sunny sky conditions is, however, computationally demanding, since the density of stochastic backward samples must match the BSDF resolution. The bidirectional Photon Map is proposed to rapidly forward-sample the BSDF, starting from the known sun direction. Its exemplary application shows a potential speed-up of 98% when compared to backward ray-tracing. © Published under licence by IOP Publishing Ltd.