Derivation of an instrumentally based geometric appearance index for the automotive industry

Mirjalili, Fereshteh; Moradian, Siamak; Ameri, Farhad

doi:10.1007/s11998-014-9608-5

Cited by 9 publications

(6 citation statements)

References 24 publications

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“…The visual gloss estimation is approximately a logarithmic function of the measured data at 20°incident angle, a linear function at 60°, and an exponential function at 85°geometry, respectively. The weighting coefficients a 1 , a 2 , and a 3 are defined as the nonlinear functions of g 60 , as expressed in equation (5), in view of the fact that the reflected light at individual geometries contributes differently to visual gloss of samples at various gloss levels and the geometry of 60°is always considered as the basic angle to describe gloss levels. In equation (5), a 1 and a 3 are logistic functions of g 60 while a 2 is a Gaussian function of g 60 , in which the parameters were finally determined by means of least-squares method, as listed in Table 4.…”

Section: Modeling Visual Glossmentioning

confidence: 99%

“…Since metallic coatings used in automotive industry present an attractive appearance, they have been a hot area of research for years. [1][2][3][4][5] Appearance, the visual perception of an object by an observer, results from the interaction of the object with incident light. The light properties, optical characteristics of the object, and human perception mechanism codetermine the interaction process.…”

Section: Introductionmentioning

confidence: 99%

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Towards a practical metric of surface gloss for metallic coatings from automotive industry

Wang

et al. 2016

J Coat Technol Res

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The specular gloss of metallic coatings from the automotive industry can be well measured by current glossmeters when the geometry is appropriately chosen from 20°, 60°, and 85°based on the gloss levels observed. However, the measurements are discontinuous and even nonmonotonic at the breakpoints dividing samples into different gloss levels in the whole range, which causes confusion and inconvenience for industry applications. In this study, attempts were made to link the measurements at the three geometries to be continuous monotonically and in the meanwhile to improve the accuracy of estimating visual gloss. A psychophysical experiment based on a magnitude method was carried out to assess the gloss of metallic coatings with different colors and textures. The visually scaled gloss data were compared with spectrophotometric measurements and instrumental specular gloss values under different geometries. With different weighing coefficients for measurements at individual geometries depending on the gloss levels, a model was proposed to describe the visual surface gloss of metallic coatings comprehensively via a practical metric based on the geometry-dependent measurements. In this way, each sample would have a unique overall gloss value highly correlated with its perceptual evaluation over the entire gloss range.

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Section: Modeling Visual Glossmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Towards a practical metric of surface gloss for metallic coatings from automotive industry

Wang

et al. 2016

J Coat Technol Res

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“…In general, when luminous light flux at a specific wavelength is incident on an optical interface with roughness, BRDF represents the reflectivity at the interface as a function of the light source position and the observation position. In more detail, as shown in (1), the BRDF can be expressed as a multivariable function of the wavelength of the incident light and vectors that define the direction of the light source and the observation position at the interface where the reflection occurs.…”

Section: Methods Of Coarseness Prediction From Measured Brdfmentioning

confidence: 99%

“…Color is an important factor for increasing the attractiveness of industrial products, such as mobile phones and automobiles. Thus, the implementation of various colors is becoming increasingly important in various industries [1]- [3]. When implementing various colors (also called albedo), maintaining the quality of the color determined by the color of the pigment is crucial.…”

Section: Introductionmentioning

confidence: 99%

Bidirectional Reflectance Distribution Function (BRDF)-Based Coarseness Prediction of Textured Metal Surface

et al. 2022

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Because coarseness has a remarkable effect on visual appearance, there has been an increasing demand for measuring quantitative coarseness based on an explicit algorithm, especially in industry. However, even in BYK-mac, a reliable measurement device for high correlation with visual inspection, its results are not clearly defined and not traceable to international standards. In addition, previous studies requiring a captured image of a sample that is sensitive to capturing conditions are not appropriate to apply to industrial sites. Therefore, in this paper, a novel method for predicting coarseness by measuring only the color and the bidirectional reflectance distribution function (BRDF) is presented. The proposed method generates images using illumination optical analysis by applying the BRDF, which is insensitive to the capturing conditions, so it can be reliably applied to industrial sites with various measurement disturbances. The proposed coarseness prediction workflow was verified based on a comparison of the predicted coarseness values of 56 samples with seven levels of roughness for each of the eight colors and the measured values using BYK-mac. Images generated from illumination optical analysis through BRDF of the prepared sample showed lower brightness on the rougher surface, similar to the BRDF measurement results. The results of the measurement and comparison show that the coarseness orders for each color are similar to each other and that the coarseness variations according to roughness levels are also similar, with a coefficient of determination, R 2 , of 0.9374.

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“…A designed uniform lightness scale was utilized to quantify the samples' specular gloss visually [25][26][27]. This scale was composed of eight 10 * 20 cm 2 gray matte polyester fabrics having the same chromaticity and varying only in lightness values [28].…”

Section: Methodsmentioning

confidence: 99%

Development of a perceptually uniform physical scale for visual assessment of specular gloss

Mohammadalizadeh¹,

Mirjalili²,

Ameri³

et al. 2021

Phys. Scr.

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Measuring gloss, visually or instrumentally, has been a challenge in many manufacturing and service industries. However, there exists no standardized method for visual evaluation of equidistance specular gloss. This study aimed to design and prepare a psychometric visually equispaced specular gloss scale for the visual measurement of gloss or any other geometric appearance attribute. To this end, a series of lithographically printed black papers, with different levels of gloss from low to high, were prepared to constitute a visually uniform specular gloss scale. Fourteen observers visually quantified the scale in a unidirectional illumination at three different geometries. Analyzing the results shows that the 60° geometry can quantify the equivalent specular gloss efficiently. A uniform specular gloss scale was prepared by assessing the prepared scale visually under the unidirectional illumination at the 60° geometry. Such a visually uniform specular gloss scale could be employed to develop a standard visual evaluation method of specular gloss in all related industries.

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Derivation of an instrumentally based geometric appearance index for the automotive industry

Cited by 9 publications

References 24 publications

Towards a practical metric of surface gloss for metallic coatings from automotive industry

Towards a practical metric of surface gloss for metallic coatings from automotive industry

Bidirectional Reflectance Distribution Function (BRDF)-Based Coarseness Prediction of Textured Metal Surface

Development of a perceptually uniform physical scale for visual assessment of specular gloss

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