Browsing by Author "Gigilashvili, Davit"

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    Can we Grasp the Color of Translucent Objects?
    (The Eurographics Association, 2024) Gigilashvili, Davit; Chowdhury, Dipayan; Hardeberg, Jon Yngve; Hardeberg, Jon Yngve; Rushmeier, Holly
    While colorimetry is traditionally measuring point colors, there is an increasing need to quantify colors of 3D objects in real-world scenes. 3D objects, especially translucent ones, exhibit high spatio-temporal variation in color. This raises multiple questions on how to measure color of 3D translucent objects, how to describe their color appearance, and how to quantify color differences among them. Or are these ill-posed problems in the first place? We discuss the first steps on this topic and suggest the future directions for color and appearance research.
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    Does Higher Refractive Index Mean Higher Gloss?
    (The Eurographics Association, 2024) Gigilashvili, Davit; Diaz Estrada, David Norman; Haines, Eric; Garces, Elena
    According to Fresnel equations, the amount of specular reflection at the dielectric surface depends on two factors: incident angle and the difference in refractive indices of inner and outer media. Therefore, it is often assumed that the higher the refractive index of the material, the glossier it looks. However, gloss perception is a complex process that, in addition to specular reflectance, depends on many other factors, such as object's translucency and shape. In this study, we conducted two psychophysical experiments to quantify the impact of refractive index on perceived gloss for objects with varying degrees of translucency and surface roughness. For some objects a monotonic positive relationship between refractive index and perceived gloss was observed, while for others the relationship was found to be non-monotonic. Afterward, we evaluated how the refractive index affects image cues to gloss and tried to explain psychophysical results by image statistics.
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    Using Spatial Augmented Reality to Increase Perceived Translucency of Real 3D Objects
    (The Eurographics Association, 2023) Trumpy, Giorgio; Gigilashvili, Davit; Bucciero, Alberto; Fanini, Bruno; Graf, Holger; Pescarin, Sofia; Rizvic, Selma
    Translucency is an important optical and perceptual attribute that has a significant impact on the appearance of objects and materials. Expensive and time-consuming manufacturing process is required to produce a translucent replica of an opaque real object. The human visual system has a poor ability to understand optics, and it relies on intensity distribution in the image to distinguish translucent and opaque materials. In this work we demonstrate a novel method of using spatial augmented reality to increase perceived translucency of more optically opaque real 3D objects by projecting energy patterns onto them that mimic the energy distribution of optically translucent materials. We conducted a user study to verify that the result looks convincing, and it is impossible to tell the transmitted and projected light apart. This opens promising directions for effective alteration of material appearance using projection systems, which can be used to enhance understanding and appreciation of historical artifacts.