Goniophotometric measurements : Numerical simulation for research and development applications

Mitanchey, R.; Periole, G.; Fontoynont, Marc

doi:10.1177/14771535950270040101

Cited by 4 publications

(2 citation statements)

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“…Two of them are described in more detail below. The third one was developed based on an extension of the Genelux lighting simulation software [67]. A detection hemisphere was generated on either side of a virtual sample to record BRDF (incidence side) and BTDF (emitting side) data.…”

Section: Assessment Of Bidirectional Distribution Functions Using Nummentioning

confidence: 99%

Goniophotometry and assessment of bidirectional photometric properties of complex fenestration systems

Andersen

Boer

2006

Energy and Buildings

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This paper seeks to provide an overview of the currently available assessment tools for Bidirectional Transmission or Reflection Distribution Functions (BTDFs, BRDFs) of complex fenestration systems (CFS). In the first part of the paper, the existing experimental devices (goniophotometers) developed specifically for CFS measurement are described. All but two are based on a scanning process to investigate the emerging light flux distribution, the alternative approach being based on digital imaging techniques. A critical analysis of their advantages and shortcomings is proposed to provide both researchers interested in replicating them and more generally potential users of BTDF or BRDF data with a lucid idea of the available options.The second part presents an alternative to physical measurements, made possible by using computer simulations based on ray-tracing techniques. In this case, every component of the modelled system must be of well-known geometric and material properties. Three virtual goniophotometer models are described and their validation results are analyzed.Whether they have been generated experimentally or through simulation, BTDF and BRDF data need to be processed into transmission or reflection functions that are directly related to sky and room conditions for them to be usable. The third part of the paper introduces a new BT(R)DF database management system whose aim is to become a reference resource for viewing and interpreting these complex data. The main visualization features of its interface are presented, that include a special focus on flexibility and on providing intuitive graphical information, in a similar way as for luminaires selection in electric lighting design.

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Section: Assessment Of Bidirectional Distribution Functions Using Nummentioning

confidence: 99%

Goniophotometry and assessment of bidirectional photometric properties of complex fenestration systems

Andersen

Boer

2006

Energy and Buildings

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“…Computational methods have already been used or developed for the assessment of complex glazing (see e.g. Compagnon, 1994;Mitanchey et al, 1995;Molina et al, 1995;Campbell, 1998;Kuhn et al, 2000), and have proven their usefulness and potentialities. However, they have so far never served extensively as a basis for BTDF measurement comparisons, as presented here.…”

Section: Introductionmentioning

confidence: 99%

Comparison between ray-tracing simulations and bi-directional transmission measurements on prismatic glazing

2003

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Evaluation of solar heat gain and daylight distribution through complex window and shading systems requires the determination of the Bi-directional Transmission Distribution Function (BTDF). Measurement of BTDF can be time-consuming, and inaccuracies are likely because of physical constraints and experimental adjustments. A general calculation methodology, based on more easily measurable component properties, would be preferable and would allow much more flexibility. In this paper, measurements and calculations are compared for the specific case of prismatic daylight-redirecting panels. Measurements were performed in a photogoniometer equipped with a digital-imaging detection system. A virtual copy of the photogoniometer was then constructed with commercial ray-tracing software. For the first time, an attempt is made to validate detailed bi-directional properties for a complex system by comparing an extensive set of experimental BTDF data with ray-tracing calculations. The results generally agree under a range of input and output angles to a degree adequate for evaluation of glazing systems. An analysis is presented to show that the simultaneously measured diffuse and direct components of light transmitted by the panel are properly represented. Calculations were also performed using a more realistic model of the source and an ideal model of the detector. Deviations from the photogoniometer model were small and the results were similar in form. Despite the lack of an absolute measurement standard the good agreement in results promotes confidence in both the photogoniometer and in the calculation method.

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Modelling indoor illumination by complex fenestration systems based on bidirectional photometric data

Boer

2006

Energy and Buildings

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Goniophotometric measurements : Numerical simulation for research and development applications

Cited by 4 publications

References 0 publications

Goniophotometry and assessment of bidirectional photometric properties of complex fenestration systems

Goniophotometry and assessment of bidirectional photometric properties of complex fenestration systems

Comparison between ray-tracing simulations and bi-directional transmission measurements on prismatic glazing

Modelling indoor illumination by complex fenestration systems based on bidirectional photometric data

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