Bidirectional reflectance distribution function measurements and analysis of retroreflective materials

Belcour, Laurent; Pacanowski, Romain; Delahaie, Marion; Laville-Geay, Aude; Eupherte, Laure

doi:10.1364/josaa.31.002561

Cited by 15 publications

(14 citation statements)

References 46 publications

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“…Functional descriptions of the BSDF allow to hide the geometric complexity of retro-reflective structures. Numerous analytical [26], numerical [27][28][29], and empirical [30] models for particular cases of retro-reflection have been proposed but are of no general applicability.…”

Section: Modelling Retro-reflectionmentioning

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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Section: Modelling Retro-reflectionmentioning

confidence: 99%

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

Grobe

2018

Energy and Buildings

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“…The detector used in these devices is usually based on spectroradiometers/diode-arrays and can provide better precision/sensitivity to light variation as compared to the image-based techniques. Because these devices make use of multi-axis motorised stages/robots (Belcour et al , 2014; Hünerhoff et al , 2006) to move around the light source, detector and sample, it makes the capture process slow (tens of hours) and impractical for human skin measurements.…”

Section: Review Of Existing Techniquesmentioning

confidence: 99%

BRDF of human skin in the visible spectrum

Sohaib

Broadbent

Farooq

et al. 2017

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Purpose Significant research has been carried out in terms of development of new bidirectional reflectance distribution function (BRDF) instruments; however, there is still little research available regarding spectral BRDF measurements of human skin. This study aims to investigate the variation in human skin reflectance using a new fibre optic-based spectral-BRDF measurement device. Design/methodology/approach Design of this system mainly involves use of multiple fibre optics to illuminate and detect light reflected from a sample, whereas a hemispherical dome was 3D printed to mount the fibres at various slant/tilt angles. To investigate the spectral differences in BRDF of human skin, 3 narrowband filters in the visible spectrum were used, whereas measurements were taken from the back of the hand for Caucasian and Asian skin types. Findings The experiments demonstrate that the BRDF of human skin varies with wavelengths in the visible spectrum and it is also different for Caucasian and Asian skin types. Both skin types exhibit off-specular reflection with increase in angle of incidence and show less variation with respect to viewing angles when the angle of incidence is normal to the surface. Research implications A database of spectral BRDF measurements of human skin will help not only in creating realistic skin renderings but also in development of novel skin reflectance models for biomedical and machine vision applications. The measurements would also provide means to validate the predictions from existing light transport/spectral simulation models for human skin and will ultimately help in the accurate diagnosis and simulation of various skin disorders. Originality/value The proposed system provides fast scatter measurements by utilising multiple fibres to detect light simultaneously at different angles while also allowing easy switching between incident light directions. Due to its flexible design and contact-based measurements, the device is independent of errors due to sample movements and does not require any image registration. Also, measurements taken from the device show that the BRDF of skin varies significantly in the visible spectrum and it is different for Caucasian and Asian skin types.

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“…His solution adopts a retroreflective screen sheet to make the camera in sensitive to the specimen position. The scattering effect of the retroreflective glass beads [131,132] also helped in the visualization of the defects. This solu tion offers an interesting idea for the work of light signal recovery from a shiny surface.…”

Section: 12]mentioning

confidence: 99%

“…We also use this product in our study (see Appendix B for the specifications). A study from [131,132] shows that there are some light scattering from the glass bead retroreflective tape; mainly, the light is scattered from the front bead surface and the exposed surface of the substrate in the gaps.…”

Section: Retroreflective Technologiesmentioning

confidence: 99%

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Novel techniques for laser doppler vibrometry for vibrating shiny and mirror surfaces

Agusanto¹

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Bidirectional reflectance distribution function measurements and analysis of retroreflective materials

Cited by 15 publications

References 46 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

BRDF of human skin in the visible spectrum

Novel techniques for laser doppler vibrometry for vibrating shiny and mirror surfaces

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