Browsing by Author "Filip, Jiri"

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    Effects of Surface Anisotropy on Perception of Car Body Attractiveness
    (The Eurographics Association, 2018) Filip, Jiri; Kolafová, Martina; Fu, Hongbo and Ghosh, Abhijeet and Kopf, Johannes
    In the automotive industry effect coatings are used to introduce customized product design, visually communicating the unique impression of a car. Industrial effect coatings systems achieve primarily a globally isotropic appearance, i.e., surface appearance that does not change when material rotates around its normal. To the contrary, anisotropic appearance exhibits variable behavior due to oriented structural elements. This paper studies to what extent anisotropic appearance improves a visual impression of a car body beyond a standard isotropic one. We ran several psychophysical studies identifying the proper alignment of an anisotropic axis over a car body, showing that regardless of the illumination conditions, subjects always preferred an anisotropy axis orthogonal to car body orientation. The majority of subjects also found the anisotropic appearance more visually appealing than the isotropic one.
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    A Psychophysical Analysis of Fabricated Anisotropic Appearance
    (The Eurographics Association, 2019) Filip, Jiri; Kolafová, Martina; Vávra, Radomir; Lee, Jehee and Theobalt, Christian and Wetzstein, Gordon
    Many materials change surface appearance when observed for fixed viewing and lighting directions while rotating around its normal. Such distinct anisotropic behavior manifests itself as changes in textural color and intensity. These effects are due to structural elements introducing azimuthally-dependent behavior. However, each material and finishing technique has its unique anisotropic properties which are often difficult to control. To avoid this problem, we study controlled anisotropic appearance introduced by means of 3D printing. Our work tends to link perception of directionality with perception of anisotropic reflectance effect it causes. We simulate two types of structure-based anisotropic effects, which are related to directional principles found in real-world materials. For each type, we create a set of test surfaces by controlling the printed anisotropy level and assess them in a psychophysical study to identify a perceptual scale of anisotropy. The generality of these scales is then verified by means of anisotropic surfaces appearance capturing using bidirectional texture function and its analysis on 3D objects. Eventually, we relate the perceptual scale of anisotropy to a computational feature obtained directly from anisotropic highlights observed in the captured reflectance data. The feature is validated using a psychophysical study analyzing visibility of anisotropic reflectance effects.