Glossiness Perception Enhanced by Retinal-Image Motion from Object-Motion and Self-Motion

Specular highlight, which is one of physical correlates of glossiness perception, moves on an object surface depending on the illumination, viewpoint and motion of the object. We aimed to investigate effects of retinal-image motions induced by self-motion or object motion on glossiness perception. One of seven lumpy spheres with different specular reflectance was presented for a trial (6s). The sphere was either stationary or rotated back and forth at 0.25Hz on a CRT display as retinal-image motion, where we simulated lateral viewpoint motion in 15cm range under three stationary point-lights. Eight observers perceived it either without or with head motion, which was monitored by a magnetic 3D tracker at 120Hz and sphere's retinal-image motion was veridically synchronized with the self-motion. They were asked to rate its glossiness using visual-analog scale. We found that the perceived glossiness was significantly higher with retinal-image motions than without them. However, self-motion and valid motion parallax did not enhance the glossiness in comparison with only retinal-image motions. These results suggest that retinal-image motion of structural surface or change of highlights enhances the glossiness perception regardless of whether it is caused by object-motion or self-motion, and that the valid motion parallax has no superiority.