摘要：The transmission and distribution of light through Complex Fenestration Systems (CFS) impacts visual comfort, solar gains and the overall energy performance of buildings. For most fenestration, scattering of light can be approximated as the optical property of a thin surface, the Bidirectional Scattering Distribution Function (BSDF). It is modelled in simulation software to replicate the optical behaviour of materials and surface finishes. Data-driven BSDF models are a generic means to model the irregular scattering by CFS employing measured or computed data sets. Even though measurements are preferred due to the realistic values they provide it is not always possible to measure the light scatter in all incident directions. In contrast, numerical simulations have virtually no limitations; however, at the cost of lower reliability. A hybrid approach, combining both, was therefore proposed. The BSDF of a CFS was measured for incident elevation angles from 0° to 60°. For incident elevation angles from 0° to 85°, the BSDF of the sample was computed. The BSDF acquired by both techniques in the overlapping range of directions between 0° to 60° was compared and revealed good qualitative accordance. The variance of the direct-hemispherical reflection and transmission based on the two techniques was between 3% and 28%. A hybrid data set was then generated, utilizing measurements where possible and simulations where instrumentation could not provide reliable data. A data-driven model based on this data set was implemented in simulation software. This hybrid model was tested by comparison with the geometrical model of the sample and measurements. The hybrid approach to BSDF modelling shall support the utilization of BSDF models based on measured data by selectively overcoming the lack of reliable measured or extrapolated data.
关键词：BSDF; BRDF; BTDF; geometric optics; scattering; complex fenestration systems
