Glossy Materials Research Articles

Analysis of Gloss Unevenness and Bidirectional Reflectance Distribution Function in Specular Reflection.

Gloss is associated significantly with material appearance, and observers often focus on gloss unevenness. Gloss unevenness is the intensity distribution of reflected light observed within a highlight area, that is, the variability. However, it cannot be analyzed easily because it exists only within the highlight area and varies in appearance across the reflection angles. In recent years, gloss has been analyzed in terms of the intensity of specular reflection and its angular spread, or the bidirectional reflectance distribution function (BRDF). In this study, we develop an apparatus to measure gloss unevenness that can alter the angle with an angular resolution of 0.02°. Additionally, we analyze the gloss unevenness and BRDF in terms of specular reflection. Using a high angular resolution, we measure and analyze high-gloss materials, such as mirrors and plastics, and glossy materials, such as photo-like inkjet paper and coated paper. Our results show that the magnitude of gloss unevenness is the largest at angles marginally off the center of the specular reflection angle. We discuss an approach for physically defining gloss unevenness based on the BRDF.

Hemispherical harmonic illumination and reflectance angular spectrum.

Light scattering plays an important role in physics, with wide applications in science and engineering. However, accurate and effective modeling of scattering remains a great challenge. In this study, we exploited the rendering equation using hemispherical harmonics to demonstrate an angular frequency representation that directly depicts scattering in a two-dimensional spectrum, free from any underlying assumptions. This representation offers a compact and intuitive characterization of mirror reflection, isotropic scattering, and anisotropic emission. The robust support of theoretical proofs and data-driven experimental results establishes the broad applicability of our computational model in conducting scattering analyses across diffuse, specular, and glossy materials. With the capability to characterize the scattering in angular frequency domain, we expect our proposed model to emerge as an essential tool in various domains, including surface feature recognition, reflectance data compression, and computer rendering.

Decorrelating ReSTIR Samplers via MCMC Mutations

Monte Carlo rendering algorithms often utilize correlations between pixels to improve efficiency and enhance image quality. For real-time applications in particular, repeated reservoir resampling offers a powerful framework to reuse samples both spatially in an image and temporally across multiple frames. While such techniques achieve equal-error up to 100× faster for real-time direct lighting [Bitterli et al. 2020 ] and global illumination [Ouyang et al. 2021 ; Lin et al. 2021 ], they are still far from optimal. For instance, spatiotemporal resampling often introduces noticeable correlation artifacts, while reservoirs holding more than one sample suffer from impoverishment in the form of duplicate samples. We demonstrate how interleaving Markov Chain Monte Carlo (MCMC) mutations with reservoir resampling helps alleviate these issues, especially in scenes with glossy materials and difficult-to-sample lighting. Moreover, our approach does not introduce any bias, and in practice, we find considerable improvement in image quality with just a single mutation per reservoir sample in each frame.

The perception of translucency from surface gloss

Translucent objects (like fruit and wax) reflect and transmit incident light to generate complex retinal image structure. Understanding how we visually perceive translucency from these images is challenging, but previous studies have demonstrated that perceived shape and shading is important for perceiving translucency. We considered the possibility that perceived translucency might also depend on 3D shape inferred from surface gloss (i.e., shape from specular highlights). Here, we performed experiments to test whether interactions between specular and non-specular image properties generated by different 3D shape information influences perceived translucency. Results revealed that perceived translucency could be explained by incongruence in 3D shape used to generate specular and non-specular image components. We proposed a new computational model based on measurable image features informative of shading relative to specular highlights that accounted for 59% of the variability in judgments of perceived translucency from the result of 10-fold cross validation. This model was found to outperform other models based on explicit subjective measures of perceived surface shape, suggesting it implicitly taps much of the relevant geometric information necessary for predicting observer judgments of translucency for glossy materials. These results provide new insight into how the visual system might infer translucency from the structure of specular and non-specular shading generated by glossy semi-opaque materials.

Free-viewpoint Indoor Neural Relighting from Multi-view Stereo

We introduce a neural relighting algorithm for captured indoors scenes, that allows interactive free-viewpoint navigation. Our method allows illumination to be changed synthetically, while coherently rendering cast shadows and complex glossy materials. We start with multiple images of the scene and a three-dimensional mesh obtained by multi-view stereo (MVS) reconstruction. We assume that lighting is well explained as the sum of a view-independent diffuse component and a view-dependent glossy term concentrated around the mirror reflection direction. We design a convolutional network around input feature maps that facilitate learning of an implicit representation of scene materials and illumination, enabling both relighting and free-viewpoint navigation. We generate these input maps by exploiting the best elements of both image-based and physically based rendering. We sample the input views to estimate diffuse scene irradiance, and compute the new illumination caused by user-specified light sources using path tracing. To facilitate the network's understanding of materials and synthesize plausible glossy reflections, we reproject the views and compute mirror images . We train the network on a synthetic dataset where each scene is also reconstructed with MVS. We show results of our algorithm relighting real indoor scenes and performing free-viewpoint navigation with complex and realistic glossy reflections, which so far remained out of reach for view-synthesis techniques.

Antithetic sampling for Monte Carlo differentiable rendering

Stochastic sampling of light transport paths is key to Monte Carlo forward rendering, and previous studies have led to mature techniques capable of drawing high-contribution light paths in complex scenes. These sampling techniques have also been applied to differentiable rendering. In this paper, we demonstrate that path sampling techniques developed for forward rendering can become inefficient for differentiable rendering of glossy materials---especially when estimating derivatives with respect to global scene geometries. To address this problem, we introduce antithetic sampling of BSDFs and light-transport paths, allowing significantly faster convergence and can be easily integrated into existing differentiable rendering pipelines. We validate our method by comparing our derivative estimates to those generated with existing unbiased techniques. Further, we demonstrate the effectiveness of our technique by providing equal-quality and equal-time comparisons with existing sampling methods.

Aesthetic Preference for Glossy Materials: An Attempted Replication and Extension.

The psychology of art and aesthetics has a long-standing interest in how low-level features, such as symmetry, curvature, and color, affect people’s aesthetic experience. Recent research in this tradition suggests that people find glossy, shiny objects and materials more attractive than flat, matte ones. The present experiment sought to replicate and extend research on the attractiveness of images printed on glossy and flat paper. To control for several possible confounding factors, glossiness was manipulated between-person and varied with methods that held constant factors like weight, color quality, and resolution. To extend past work, we explored art expertise and Openness to Experience as potential moderators. A sample of 100 adults viewed landscape photographs on either high-gloss photo paper or on identical paper in which a flat, matte spray finish had been applied. Ratings of attractiveness showed weak evidence for replication. People rated the glossy pictures as more attractive than the matte ones, but the effect size was small (d = −0.23 [−0.62, 0.16]) and not statistically significant. Attractiveness ratings were significantly moderated, however, by individual differences in the aesthetic appreciation facet of Openness to Experience. When aesthetic appreciation was high, people found the images attractive regardless of condition; when it was low, people strongly preferred the glossy images over the matte ones, thus showing the classic glossiness effect. We conclude with some methodological caveats for future research.

Neural reflectance transformation imaging

Reflectance transformation imaging (RTI) is a computational photography technique widely used in the cultural heritage and material science domains to characterize relieved surfaces. It basically consists of capturing multiple images from a fixed viewpoint with varying lights. Handling the potentially huge amount of information stored in an RTI acquisition that consists typically of 50–100 RGB values per pixel, allowing data exchange, interactive visualization, and material analysis, is not easy. The solution used in practical applications consists of creating “relightable images” by approximating the pixel information with a function of the light direction, encoded with a small number of parameters. This encoding allows the estimation of images relighted from novel, arbitrary lights, with a quality that, however, is not always satisfactory. In this paper, we present NeuralRTI, a framework for pixel-based encoding and relighting of RTI data. Using a simple autoencoder architecture, we show that it is possible to obtain a highly compressed representation that better preserves the original information and provides increased quality of virtual images relighted from novel directions, especially in the case of challenging glossy materials. We also address the problem of validating the relight quality on different surfaces, proposing a specific benchmark, SynthRTI, including image collections synthetically created with physical-based rendering and featuring objects with different materials and geometric complexity. On this dataset and as well on a collection of real acquisitions performed on heterogeneous surfaces, we demonstrate the advantages of the proposed relightable image encoding.

Fats are Glossy but Does Glossiness Imply Fatness? The Influence of Packaging Glossiness on Food Perceptions.

This research brings together two research streams, one focusing on the influence of a diverse set of packaging attributes (e.g., shape, size, color, etc.) on perceptions of packaged food and the second one on the up- and downsides of using glossy materials, which are often studied in a non-food context. The current research deals with the influence of glossy (versus matte) food packages on consumers’ perceptions of the food inside the package. With one online survey and one quasi-experiment, we show that consumers draw inferences on the food’s fat level from the package surface, in that glossy packages are seen as a signal of fatness. This association is specific; consumers do not associate glossiness with every unhealthy product aspect. Sugar levels are unaffected by the package surface. However, due to the higher inferred fat level, a product in a glossy package is perceived to be less healthy, less tasty, and low in quality and product expensiveness. Thus, these findings suggest that glossy (versus matte) food packages mainly serve as a signal of negative product qualities.

A highlight effects generation model for translucent materials perception based on directional subsurface scattering

Usually the highlights can be calculated with the specular term of the bidirectional reflectance distribution functions developed for glossy or matte materials. However, as for the translucent materials, complex appearance could be caused by the scattering of light inside the medium. An efficient highlight generation model is presented to simulate the highlight effects on smooth or rough surfaces or around the boundaries of objects made from translucent materials. The presented model is derived from the directional dipole model approximation of the diffusive part of the bidirectional scattering surface reflectance distribution function. Unlike the previous specular reflection models, the presented model builds a relationship between the highlights and the scattered lights inside the medium by considering the refracted ray of the incident point and the ray toward the emergent point, which could represent the variation in fluence due to the internal scattering at the surface. By integrating a rendering process with the directional dipole model, the resulting highlight effects term could be represented in a similar way by the specular term of a bidirectional reflectance distribution function model. The number and the strength of the generated highlight pixels were compared among typical highlight generation models. It is demonstrated that the presented model could generate highlight effects at the appropriate positions and enhance the perceptual translucency of specific edge areas greatly.

Contextual effects in human gloss perception

The well-known simultaneous contrast effect describes how surrounding surfaces influence lightness perception. Similar contextual effects are ubiquitous in the lightness literature. Contextual effects in gloss perception however, have not yet been studied intensively. Here, we describe two distinct studies that investigate the role of spatial interactions between different glossy materials. In a first study we produced real surfaces that contain two different materials and compared perceived gloss in two conditions: in isolation and in context with a second material. Our results provide strong evidence that the context largely influences perceived gloss. Gloss ratings of identical materials differed depending on the presentation mode. In a second study we wished to quantify the strength of these contextual effects using Maximum likelihood conjoint measurement. We used glossy versions of the simultaneous contrast display and again found strong influences of albedo and gloss of the surroundings on perceived gloss and lightness. Both studies hint towards a profound influence of the context on perceived gloss. Investigating spatial interactions between materials within a scene has largely been studied in the lightness literature but only received moderate attention in the gloss literature. Our results provide confirmatory evidence that perceived gloss is shaped by other materials in the scene.

Infrared thermographic measurement of the surface temperature and emissivity of glossy materials

Determination of the surface temperature and emissivity of glossy materials is a complicated task due to the relatively wide range of emissivity values and the reflection of infrared radiation from surrounding objects. As a consequence, standard methods used in infrared thermography are not applicable. In this article, an alternative method is proposed for the measurement of the surface temperature and emissivity of glossy materials used in the external structures of buildings that is based on an external source of thermal radiation. It is shown that the method gives quite accurate values of emissivity of both low- and high-emissivity glossy materials, whereas the surface temperature of low-emissivity glossy materials is less accurate and strongly depends on the accuracy of the used thermal camera.

Dip transform for 3D shape reconstruction

The paper presents a novel three-dimensional shape acquisition and reconstruction method based on the well-known Archimedes equality between fluid displacement and the submerged volume. By repeatedly dipping a shape in liquid in different orientations and measuring its volume displacement, we generate the dip transform : a novel volumetric shape representation that characterizes the object's surface. The key feature of our method is that it employs fluid displacements as the shape sensor. Unlike optical sensors, the liquid has no line-of-sight requirements, it penetrates cavities and hidden parts of the object, as well as transparent and glossy materials, thus bypassing all visibility and optical limitations of conventional scanning devices. Our new scanning approach is implemented using a dipping robot arm and a bath of water, via which it measures the water elevation. We show results of reconstructing complex 3D shapes and evaluate the quality of the reconstruction with respect to the number of dips.

국내 남성 아웃도어 웨어에 나타난 이미지 분석

This research reviewed the developmental process of domestic outdoor wear and later analyzed the images given out by men's outdoor wear. The research results are as follows. First, military supplies left by American soldiers were dyed or reformed and then worn, and daily wear were mainly worn in the 1960s. Wears made from light and waterproof materials were worn and equipments were used in the 1970s. High functioning materials which allowed simultaneous breathability, waterproof and thermal insulation functions were used for wears in the 1980s. For the jacket especially, functionality was enhanced sith zippers, snaps and velcro to prevent cold air penetration in the 1990s. Florescent piping decorations and logo decorations, and prints and colors which reflected the trend, were used to emphasize fashionity and decorativeness in the 2000s. Second, Sophisticated image emphasized urban feeling with toned-down windbreaker jackets without much detail, with down jacket and pants. Casual image expressed a relaxed feeling with windbreaker jacket, shirts, jumper, vest and pants made of cotton, mesh knit and denim. Active image emphasized functionality by brightly colored windbreaker jackets, down jacket and pants. Ethnic image expressed an exotic mood with windbreaker jackets with stylized prints, with jumper, down jacket and pants. Military image showed a strong masculine feeling with jackets adorned with epaulettes, khaki colors and camouflage prints, with jumper, T-shirts, vest, shorts and pants. Avantgarde image exuded an experimental and unique feeling with jackets made of various colors and materials, such as cotton, jersey and glossy materials, with down jacket and jersey pants.

Specular kurtosis and the perception of hazy gloss

Previous work on the perception of glossy materials has mostly focused on two dimensions: gloss strength and microscale roughness. However, more advanced reflectance models often include additional parameters for controlling the distribution of reflected light. It remains unknown whether these additional dimensions have a perceptually significant influence on appearance. In particular, among the six types of gloss suggested by Hunter in his seminal book (Hunter, 1975), “haze” remains among the less studied of potentially pertinent material cues. From a physical point of view, hazy reflections are associated with heavy-tailed, or leptokurtic, reflectance functions, as often occurs in semi-polished metals or coated materials. We have investigated gloss haze by rendering movies of irregularly shaped objects made of metallic materials exhibiting more or less leptokurtic reflectance functions. We modeled hazy metals using a two-layered glossy material model with two centered Gaussian-like lobes (Ward, 1992) of different spread. Varying both the (1) relative spread and (2) relative magnitude of the two lobes yielded a 5x5 array of different materials. Subjects rated the following qualities for each material: glossiness, blurriness, haziness, coatedness, polish, and friction. Principal component analysis of the results reveals that haziness is a distinct visual dimension orthogonal to the commonly studied glossiness and blurriness. Coatedness appears to be nearly synonymous with haziness, as this is one of the main physical causes of haze in real world materials. Polish seems to be a combination of glossiness and haziness, as materials go from dull to hazy to highly glossy during the physical polishing process. The inferred tactile quality of friction is apparently uncorrelated with haziness. Our results demonstrate that haze is indeed a distinct perceptual dimension of gloss, which is systematically related to the kurtosis of the specular lobe.

Principles of the four‐point thermographic measurement of the surface temperature and emissivity of glossy materials

AbstractThe emissivity and surface temperature of glossy materials are measured in IR thermography by covering the surface with a material with the known emissivity. The quantities can be, however, determined without using materials with the known emissivity. IR radiation is reflected from the measured glossy surface and a thermographer detects such reflection.This paper discusses the measurement of the surface temperature and emissivity of glossy materials which are used in external structures of the buildings – for instance, windows, light external walls or tiles. A four‐point method is proposed for a more accurate determination of the surface temperature and emissivity of glossy materials. Results of successful laboratory and field tests of the method are presented.Prinzipien der Vier‐Punkt‐Thermografie‐Messmethode für die Oberflächentemperatur und den Emissionsgrad glänzender Werkstoffe. Zur Messung des Emissionsgrads und der Oberflächentemperatur glänzender Werkstoffe mit der Infrarot‐Temperaturmessmethode wird die Oberfläche mit einem Material abgedeckt, dessen Emissionsgrad bekannt ist. Die Größen lassen sich jedoch auch ohne Verwendung von Materialien mit bekanntem Emissionsgrad ermitteln. Die glänzende Oberfläche des Messobjekts reflektiert IR‐Strahlung, und eine Wärmebildkamera erfasst die reflektierte Strahlung.Der vorliegende Aufsatz beschreibt die Messung der Oberflächentemperatur und des Emissionsgrads glänzender Werkstoffe für die Außenhaut von Gebäuden, beispielsweise Fenster, Leichtbaufassaden oder Fliesen. Für die präzisere Ermittlung der Oberflächentemperatur und des Emissionsgrads glänzender Werkstoffe wird eine Vier‐Punkt‐Methode vorgeschlagen. Es werden die Ergebnisse erfolgreicher Laborversuche und Feldversuche mit dieser Methode präsentiert.

A Study on the Postmodernism Tendency Expressed in Hedi Slimane's Men's Wear Design - Focusing on the Comparison Between the Collection of Dior Homme and Yves Saint Laurent -

The purpose of this study is to examine the characteristics of men``s wear designs unveiled while Hedi Slimane worked for Dior Homme and Yves Saint Laurent. The study will analyze and focusing on the modernistic characteristics in order to discover the postmodernism trends in his works. The results of the research are as follows. First, Hedi Slimane``s fashion style can be cited as grunge and punk due to the trend of expressing the subculture of postmodernism. The design features shown in Dior Homme were straight lines, leather, metallic materials and dark colors used to reinterpret a grungy punk style, romantic patterns, glossy materials, elastic leather, and bright colors were the salient features of Yves Saint Laurent. Second, the feature of cultural pluralism of postmodernism appeared as a type ethnic style. He presented this through the Third World images in the Dior Homme but Spanish matador images, Marrakech‘s images and North African images in the Yves Saint Laurent. Third, he feature of his style is metrosexual feminizing men’s fashion and breaking up gender stereotypes. I-type and X-type silhouettes that emphasize the human body and feminine design motifs such as a skirt are dominated in Dior Homme, and he completed the metrosexual style by using materials, colors and patterns such as bright feminine pink, red, laces, fur, floral and leopard prints, as well as flagrantly expressing body contour.

Virtual Spherical Gaussian Lights for Real-time Glossy Indirect Illumination

Virtual point lights VPLs are well established for real-time global illumination. However, this method suffers from spiky artifacts and flickering caused by singularities of VPLs, highly glossy materials, high-frequency textures, and discontinuous geometries. To avoid these artifacts, this paper introduces a virtual spherical Gaussian light VSGL which roughly represents a set of VPLs. For a VSGL, the total radiant intensity and positional distribution of VPLs are approximated using spherical Gaussians and a Gaussian distribution, respectively. Since this approximation can be computed using summations of VPL parameters, VSGLs can be dynamically generated using mipmapped reflective shadow maps. Our VSGL generation is simple and independent from any scene geometries. In addition, reflected radiance for a VSGL is calculated using an analytic formula. Hence, we are able to render one-bounce glossy interreflections at real-time frame rates with smaller artifacts.

Realtime Rendering Glossy to Glossy Reflections in Screen Space

Glossy to glossy reflections are lights bounced between glossy surfaces. Such directional light transports are important for humans to perceive glossy materials, but difficult to simulate. This paper proposes a new method for rendering screen-space glossy to glossy reflections in realtime. We use spherical von Mises-Fisher vMF distributions to model glossy BRDFs at surfaces, and employ screen space directional occlusion SSDO rendering framework to trace indirect light transports bounced in the screen space. As our main contributions, we derive a new parameterization of vMF distribution so as to convert the non-linear fit of multiple vMF distributions into a linear sum in the new space. Then, we present a new linear filtering technique to build MIP-maps on glossy BRDFs, which allows us to create filtered radiance transfer functions at runtime, and efficiently estimate indirect glossy to glossy reflections. We demonstrate our method in a realtime application for rendering scenes with dynamic glossy objects. Compared with screen space directional occlusion, our approach only requires one extra texture and has a negligible overhead, 3% ~ 6% loss at frame rate, but enables glossy to glossy reflections.

Verification of Applicability of Alternate Sources of Heat for Determination of the Surface Temperature and Emissivity of Glossy Materials

The value of the surface temperature and emissivity of glossy materials can be determined by the method of four points. However, in practical measurements on the peripheral walls of buildings there may occur situations where four points are not available. In such case it is possible to use alternate sources of heat.