Abstract
Static and motion optical cues have been independently shown to contribute to the appearance of material properties. The influence of mechanical information (through shape or motion cues) is less explored. We conducted experiments to investigate the contributions of, and interactions between, optical, motion, and shape information to material perception. We created novel animations of materials ranging from soft to hard bodies that broke apart differently when dropped. In Experiment 1, animations were rendered as point-light movies varying in dot density, and "full-cue" optical versions ranging from translucent glossy to opaque matte under a natural illumination field. Observers used a scale to rate each substance on 30 different attributes. In Experiment 2 we investigated the contribution of shape to attribute ratings in Experiment 1, by comparing ratings when observers were shown one frame of the animation after the point of impact versus a short movie clip around the point of impact. The results showed: (1) Strikingly, there were interactions between surface optics and substance (hard/soft bodies) for many ratings, which differed when substances were presented in motion compared to static images. (2) Perceived differences between hard and soft bodies were often significantly more pronounced for full-cue stimuli versus both point-light and static stimuli. (3) For some ratings, the motion in the full-cue stimuli overrode information provided by optics in the static images. (4) A factor analysis verified that ratings of the 30 attributes were tapping into a few underlying dimensions, which reflect the manipulated mechanical and optical material properties. Together, the results showed that neither motion nor optics/shape information alone could fully account for the results in the full-cue condition. Therefore, combining motion and optical properties appears to provide additional information about material qualities. These novel findings demonstrate a critical interaction between motion and surface optics in the perception of materials.
Meeting abstract presented at VSS 2017