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Masataka Sawayama, Taiki Fukiage, Shin'ya Nishida; Perceiving shape of thin translucent objects from spatial transmittance variation. Journal of Vision 2017;17(10):764. doi: 10.1167/17.10.764.
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© ARVO (1962-2015); The Authors (2016-present)
While human monocular 3D shape perception has traditionally been investigated using opaque objects, we frequently encounter objects with translucent material properties in our daily life. We can perceive the shape of thin translucent objects such as silk curtains and plastic bags, but the underlying visual processing remains poorly understood. The present study explored what image cues can be used to estimate the shape of translucent sheet-like objects. Consider a corrugated translucent surface with a certain degree of thickness like a veil. The light transmittance of the sheet is expected to be higher when the surface normal is toward a direction of the eye than when it is slanted with regard to the eye direction. This implies that the light transmittance of a translucent sheet can be a shape cue to estimate the surface orientation. In a psychophysical experiment we investigated whether the visual system utilized this cue. The stimulus in the experiment was synthesized by alpha-blending a natural texture with a corrugated CG sheet whose geometric structure was known. There were three transmittance conditions. Consistent condition: the light transmittance (i.e., alpha value) spatially co-varied with the slant of the CG surface. Inconsistent condition: the transmittance map was rotated 90 degrees to break the consistency. Uniform condition: the transmittance was spatially uniform. In the experiment, we estimated the perceived shape of the translucent sheet by asking observers to set a gauge probe with the apparent surface slant/tilt. Results of the experiment showed that when the transmittance of the blending was consistent with the surface slant, the perceived shape was closer to the ground truth than those under the other two conditions. The finding suggests that the spatial transmittance variation consistent with shading is an effective shape cue of translucent sheets.
Meeting abstract presented at VSS 2017
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