Establishment of a computer-controlled retroreflection measurement facility to characterize photometric properties of retroreflectors

Sametoglu, Ferhat; Celikel, Oguz

doi:10.1016/j.measurement.2008.12.007

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…1). Only a very long distance between sample and detector allows to cover the peak region of highly directional retro-reflection in such direct measurements [21].…”

Section: Measurement Techniquesmentioning

confidence: 99%

Characterization and data-driven modeling of a retro-reflective coating in Radiance

Grobe

2018

Energy and Buildings

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a b s t r a c tRetro-reflective coatings applied to blinds of reduced geometric complexity promise to provide view to the outside while effectively controlling solar gains and glare. To characterize the reflection characteristics of such coatings over the entire solar spectrum, a novel extension to a scanning gonio-photometer is developed. The extended instrument is tested and applied to measure a coating's Bidirectional Reflection Distribution Function including the region of the retro-reflected peak. The measured datasets are compiled into a data-driven reflection model for the daylight simulation software Radiance. This model is applied to illustrate the coating's effect in a comparison to purely diffuse and specular surface finishes on geometrically identical, flat blinds. Daylight supply, the probability of glare, and solar gains are assessed for an exemplary, South-oriented office under sunny sky conditions. The results indicate the potential of the coating to effectively shade direct sunlight even if applied on blinds with minimalistic geometries. The modeling technique is shown to be a general means to replicate the irregular optical properties of the coating, which cannot be represented by the standard models in daylight simulation software.

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“…1). Only a very long distance between sample and detector allows to cover the peak region of highly directional retro-reflection in such direct measurements [21].…”

Section: Measurement Techniquesmentioning

confidence: 99%

Characterization and data-driven modeling of a retro-reflective coating in Radiance

Grobe

2018

Energy and Buildings

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Calibration Scheme for Portable Retroreflectometers of Road Traffic Signs

Huang

Han³

et al. 2020

J. Phys.: Conf. Ser.

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Portable retroreflectometers are widely used for engineering measurements and are equipped with a set of work plates that are used to fit fitting curves and switch the working curve in the intrinsic software (self-calibration). The measuring principle employed is the substitution method. Therefore, the accuracy of the work plate values and curve-fitting ability of the internal software are important factors related to the accuracy of the instrument’s measurement results. A calibration scheme for portable retroreflectometers is proposed in this paper. This scheme not only considers calibration in the laboratory, but also on-site measurements. The work plate values can be obtained by a standard retroreflection measurement system, or by a matching portable retroreflectometer. When the work plate values are obtained through the matching instrument, a set of reference plate values must be obtained first. The reference plates, the color and coefficients of retroreflection of which are similar to those of the work plates, were calibrated by the standard retroreflection measurement system using the direct illuminance method. The reference plates were used to adjust the fitting curve in the internal software of the instrument. The work plates were then measured by the matching instrument to obtain a set of work plate values. The reference plates were measured by a self-calibration portable retroreflectometer, and the relative error between the instrument’s results and reference values was calculated.

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Establishment of a metric to characterize retroreflector properties using a consumer-grade colour camera

Huang

Cheng

2022

Transportation Safety and Environment

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The coefficients of retroreflection and chromaticity coordinates are critical metrics for determining the quality of a retroreflector. However, conventional retroreflection measurement techniques rely heavily on the night-time colour, size, and characteristics of the sample being measured. This complicates the measurement process and leads to deviations in the test results. In addition, chromaticity cannot be determined using this approach. Therefore, it is necessary to improve the measurement accuracy, simplify the measurement process, and achieve the measurement of the traffic sign RA and chromaticity coordinates simultaneously. In this study, an improved method for retroreflector characterisation using imaging was proposed. This allowed for the measurement of the coefficients of retroreflection and the chromaticity coordinates simultaneously, and only a white standard sample was required for calibration. The primary components of the proposed system included a lighting projector, a receiver, two motorised rotational stages, a retroreflective sample holder, and customised software that used scaling factors to convert a digital signal into sample retroreflection coefficients and retroreflective chromaticity coordinates. The experimental results indicated that the raw data output from the camera exhibited a positive correlation relationship with the luminous flux from the surface of the retroreflector. The maximum measurement errors for the retroreflection and chromaticity were −12.2 cd/(lx·m2) and −2.09%, respectively. This method was inexpensive and convenient, used a commercially available digital camera, could help to identify defects in retroreflection and chromaticity for retroreflective sheeting, and led to increased accessibility for the quality control of retroreflective sheeting.

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Establishment of a computer-controlled retroreflection measurement facility to characterize photometric properties of retroreflectors

Cited by 4 publications

References 5 publications

Characterization and data-driven modeling of a retro-reflective coating in Radiance

Characterization and data-driven modeling of a retro-reflective coating in Radiance

Calibration Scheme for Portable Retroreflectometers of Road Traffic Signs

Establishment of a metric to characterize retroreflector properties using a consumer-grade colour camera

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