2/18/2023 0 Comments Specular reflection![]() We found that the thickness of objects with specular reflectance tends to be perceptually overestimated, and thickness of transparent objects tends to be perceptually underestimated. Previously, we systematically varied the simulated material composition of objects from refractive to reflective, with different amounts of specular reflectance. These interactions between perceived shape and material properties suggest that the perception of both shape and materials depends on similar sources of image-based information. Rather than observers matching internal experiences of refractivity, these researchers found that observers tended to match surfaces directly based on similarity in image cues: specular reflections and the distortion field.įurther studies have used gauge figure tasks to estimate variations in perceived surface slant (i.e., surface curvature) and found that the 3D shape of objects with semi-opaque reflectance properties tends to be perceptually underestimated ( Chowdhury et al., 2017 Schlüter and Faul, 2019). ![]() Another study proposed that background distortions alone are not sufficient for perceiving RI because they depend on both the shape and distance of the object from the background ( Schlüter and Faul, 2014). Researchers proposed that perception of transparency was estimated based on the background distortion seen through transparent objects ( Fleming et al., 2011 Fleming, 2014 Todd and Norman, 2019). How do the refractive and reflective properties of transparent surfaces influence the perception of their 3D shape?Īlthough perceptual judgments of transparency loosely correspond to their refractive index (RI) ( Fleming et al., 2011), human observers are not able to accurately estimate the RI of transparent objects. It is also complex because natural transparent objects tend to reflect specular reflections off their surfaces. Images of thick transparent objects have complex structure attributed to their refractive power, shape and material composition ( Fleming et al., 2011 Schlüter and Faul, 2014). In other words, glossier surfaces tend to be perceived as bumpier than diffuse surfaces.Īnother surface property that influences perceived shape is the refractive nature of transparent objects. Adding sharp specular reflections was found to increase perceived convexity in excess of the surface's true curvature ( Mooney and Anderson, 2014). However, some researchers have shown the opposite pattern of results can occur ( Mooney and Anderson, 2014). For example, previous work has shown that the perceived 3D shape of opaque objects tends to be underestimated ( Koenderink and van Doorn, 1992 De Haan et al., 1995 Todd et al., 2004 Bernhard et al., 2016). Although we have vivid experiences of surfaces with material properties (e.g., glossy, matte, opaque, or transparent), observers are often biased in their report of either a surface's material appearance or 3D shape ( Nishida and Shinya, 1998 Belhumeur et al., 1999 Nefs et al., 2006 Khang et al., 2007 Vangorp et al., 2007 Wijntjes and Pont, 2010 Mooney and Anderson, 2014 Dövencioglu et al., 2015 Marlow et al., 2015 Todd et al., 2015). Images result from the complex interplay between illumination and a surface's material composition and three-dimensional (3D) shape. The results were also explained by the variance in local RMS contrast in stimulus images but may depend on overall luminance and contrast of the surrounding light field. Surprisingly, the ratio of specular reflection to refractive component was almost equal to that of ordinary glass and ice, which promote correct percepts of 3D shape. We investigated the relative dominance of specular reflection and refractive distortions in the perception of shape. In an object with both elements, such as glass, the two optical properties may complement each other to support reliable perception of 3D shape. We have found in past work that relevant sources of scene complexity have differential effects on 3D shape perception, with specular reflections increasing perceived thickness, and refractive distortions decreasing perceived thickness. Specular reflections and refractive distortions are complex image properties of solid transparent objects, but despite this complexity, we readily perceive the 3D shapes of these objects (e.g., glass and clear plastic). 3Electronics-Inspired Interdisciplinary Research Institute, Toyohashi University of Technology, Toyohashi, Japan.2School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia.1Department of Computer Science and Engineering, Toyohashi University of Technology, Toyohashi, Japan. ![]() ![]() Masakazu Ohara 1, Juno Kim 2 and Kowa Koida 1,3 * ![]()
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