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Michael Crognale; Reflections on Depth from Reflections: Discounting Surfaces. Journal of Vision 2018;18(10):495. doi: 10.1167/18.10.495.
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© ARVO (1962-2015); The Authors (2016-present)
Many surfaces produce both specular and diffuse reflections from point-sources of light. It has been proposed that these specular components provide information about both the source (e.g. for achieving color constancy) and the surface (e.g. both texture and shape). However, specular reflections might also be treated by the visual system as objects (or images) of interest themselves. It is well known that images of extended objects reflected from curved surfaces such as mirrors can be perceived at various depths depending upon the curvature of the surface. The appearance of depth is greatly enhanced by the addition of disparity arising out of the optical geometry. However, most specular reflections produce only weak stereoscopic depth effects since the reflections appear to be correctly attributed to a distant source of light reflected from the surface. In other words, disparity in this case is discounted with regard to depth but may be used to infer surface curvature. But, what happens to the disparity information if the information about the surface is reduced or removed? Here we report observations of depth from stereopsis of specular reflection from curved surfaces that have been placed into rotational motion so as to obscure the surface cues. This effect is easily demonstrated with a chrome-plated version of a currently popular toy, called a "finger spinner" or a "fidget-spinner". If the device is spun rapidly in the presence of a point-light source then the surface features of the spinner are obscured yet the specular reflections remain. The result is that the reflections from convex and concave surface features produce patterns that are seen in striking depth that far exceeds the dimensions of the toy itself. Further investigations show generalization to any curved surface as predicted by the geometry and that the effect depends upon surface information.
Meeting abstract presented at VSS 2018
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