Comparing Photometric Distributions

Ashdown, Ian

doi:10.1080/00994480.2000.10748478

Cited by 4 publications

(4 citation statements)

References 16 publications

(15 reference statements)

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“…Among the existing metrics for global accordance over the hemispherical distribution [22,23], a quality index is proposed for applications in the characterization of light sources [24]:…”

Section: Comparison Metrics For Directionally Resolved Bsdfmentioning

confidence: 99%

Accordance of Light Scattering from Design and De-Facto Variants of a Daylight Redirecting Component

Noback¹,

Grobe²,

Wittkopf³

2016

Buildings

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Abstract:For the systematic development of a small-scale daylight-redirecting louver system the impact of manufacturing on light scattering characteristics has to be quantified, localized and understood. In this research, the accordance of the measured scattering distributions of a de-facto production sample V1 with the computed predictions based on its design geometry V2 are quantified for selected incident light directions. A metric describing the global accordance of distributions is adapted to quantify their overall difference. A novel metric of local accordance allows further analysis. A particular low global accordance between V1 and V2 is found for an incident elevationTo test the hypothesis that this result can be explained by observed geometric deviations, a simulation model V3 replicating these is compared to the design. The hypothesis is supported by the resulting high degree of accordance. The low local accordance for individual outgoing light directions indicates geometric non-uniformity of the sample V1. This method has been found useful for product development and quality assurance. Beyond their application in the proposed method, global and local accordance have potential applications in all fields of light scattering measurements.

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“…Among the existing metrics for global accordance over the hemispherical distribution [22,23], a quality index is proposed for applications in the characterization of light sources [24]:…”

Section: Comparison Metrics For Directionally Resolved Bsdfmentioning

confidence: 99%

Accordance of Light Scattering from Design and De-Facto Variants of a Daylight Redirecting Component

Noback¹,

Grobe²,

Wittkopf³

2016

Buildings

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“…The zonal distance values can also be applied to zones with any theta-and phirange. The definition range then covers spherical rectangles, and the term of the solid angle standardisation appearing in equations 5 to 7 will change from 1 4 sr to 1 AE k, l .…”

Section: New Local Difference Measuresmentioning

confidence: 99%

“…Literature on the subject of LID comparisons is hardly available. According to Ashdown, 1 various methods of shape analysis originating from the field of pattern recognition are, in principle, suitable for LID comparisons. He uses for the comparison the so-called partial Haussdorff distance, which is employed for quantifying simple polygonal shapes, without stating detailed reasons.…”

Section: Introductionmentioning

confidence: 99%

Comparison of luminous intensity distributions

Gassmann¹,

Krueger²,

Bergen³

et al. 2016

Lighting Research & Technology

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Luminous intensity distributions enable an evaluation of the spatial radiation characteristic of a light source. This radiation characteristic is determined by the structural properties of the light source, its operating parameters and the properties of the measuring system. This paper describes some possible methods and rules for comparing luminous intensity distributions. The focus is on the development of calculation rules for quantifying the differences between two luminous intensity distributions. The difference measures developed allow the user to establish an objective comparison between luminous intensity distributions, this comparison being completely independent of the measuring system, the properties of the luminous intensity distributions and the users themselves. Further, the dependence of the properties of luminous intensity distributions resulting from measurement practice, such as adjustment uncertainties, regions that cannot be covered or measured, deviations of the total luminous flux, data noise and resolution differences, are discussed, and appropriate pre-processing and correction steps proposed. In addition, various visualisations of the differences between two luminous intensity distributions are demonstrated and the functionality of the difference measures developed is documented.

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“…There have been methods proposed in the past for comparing luminous intensity distribution, most notably by Ashdown. 3 However, Ashdown's method uses a three-dimensional shape comparison to compare the distributions as photometric solids and it produces a metric that is not suitable to use in a practical sense.…”

Section: Comparing Luminous Intensity Distributionsmentioning

confidence: 99%

A practical method of comparing luminous intensity distributions

Bergen

2012

Lighting Research & Technology

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In the field of goniophotometry, as in many other measurement disciplines, there is an increasing need for laboratories to become ISO-17025 accredited. This involves, amongst other things, characterisation of the goniophotometric measurement for uncertainty analysis and laboratory intercomparisons. Simple comparison of the luminous intensity measurements, however, can lead to large errors where there is a steep luminous intensity gradient when the only difference between the two sets of measurements is a small discrepancy in alignment. Given the difficulty in mounting and aligning some types of luminaires, this makes uncertainty analysis and intercomparisons difficult. Furthermore, the work of several CIE Division 2 Technical Committees (e.g. TC2-62) highlights the need to compare the measurements made on both far-field and near-field goniophotometers. This paper introduces a metric for comparison of two luminous intensity distributions that isolates and removes discrepancies that arise both from misalignment and also the difference in absolute calibration scales or the luminous flux output of the source. Moreover, these discrepancies are reported as part of the metric, so that a complete comparison of the sets of measurements is possible.

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Comparing Photometric Distributions

Cited by 4 publications

References 16 publications

Accordance of Light Scattering from Design and De-Facto Variants of a Daylight Redirecting Component

Accordance of Light Scattering from Design and De-Facto Variants of a Daylight Redirecting Component

Comparison of luminous intensity distributions

A practical method of comparing luminous intensity distributions

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