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A hybrid data-driven BSDF model to predict light transmission through complex fenestration systems including high incident directions

A hybrid data-driven BSDF model to predict light transmission through complex fenestration... The transmission and distribution of light through Complex Fenestration Systems (CFSs) 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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Facade Design and Engineering iospress

A hybrid data-driven BSDF model to predict light transmission through complex fenestration systems including high incident directions

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Publisher
IOS Press
Copyright
Copyright © 2016 IOS Press and the authors. All rights reserved
ISSN
2213-302X
eISSN
2213-3038
DOI
10.3233/FDE-161191
Publisher site
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Abstract

The transmission and distribution of light through Complex Fenestration Systems (CFSs) 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.

Journal

Journal of Facade Design and Engineering – iospress

Published: Jan 1, 2017

References

  • Bi-directional transmission properties of venetian blinds: Experimental assessment compared to ray-tracing calculations
    Andersen
  • Inclusion of the specular component in the assessment of bidirectional distribution functions based on digital imaging
    Andersen
  • Goniophotometry and Assessment of bidirectional photometric properties of complex fenestration systems
    Andersen