Abstract
When an observer moves laterally in a scene, edges of foreground objects occlude or reveal parts of the background. These accretion-deletion effects have been studied for large motions and are believed to provide a strong ordinal depth cue. Here we examine accretion-deletion effects that result from very small head movements such as occur during small postural adjustments. We call such motion "microparallax". An example of the magnitude we consider is that the eye moves laterally over a distance of a few mm, and is viewing a foreground and background surface at distance one and two meters, respectively. The stimuli in our experiment consisted of a densely textured foreground and background in a bipartite field. The textures consist of lines and curve fragments of random orientations and position. A range of relative retinal image speeds was used, with means from 0.1 to 0.5 deg/sec, and motion duration of about 600 ms. We found that accretion-deletion effects are a strong cue to ordinal depth in these conditions. The stimuli also contained rendered defocus blur, namely either the foreground or background object was blurred by a variable amount and the edge blur provided a potential ordinal depth cue [Mather, 1996]. The accretion-deletion cue was generally preferred over the blur cue. Our findings suggest that accretion-deletion is an important cue to depth even in situations of tiny postural adjustments of a few mm where one normally does not consider the observer to be moving.
Meeting abstract presented at VSS 2018