Perception of Scene Layout from Optical Contact, Shadows, and Motion

Abstract

Kersten et al (1997 Perception 26 171-192) found that the perceived motion of an object in a 3-D scene was determined by the motion of a shadow. In the present study, we compared the effect of a shadow to that of a second object on the ground in determining the perceived position in depth of a floating object in both dynamic and stationary scenes. Changing the second (lower) object from textured to dark increased the influence of the second object on the judged position of the first object. Giving the second object zero thickness had this effect only if it was also dark. Variations in the height of the floating object were important with a second object but not with a shadow, in motion scenes. With alternative shadows present, the position of the floating object was determined primarily by matching speeds, with matching sizes as a secondary factor. These results show some similarities but important differences between the effect of a second object and that of a shadow.

The ground dominance effect in the perception of relative distance in 3-D scenes is mainly due to characteristics of the ground surface

“…Our results concur with those of an increasing number of studies in recent years demonstrating the importance of the ground surface in scene perception (e.g., Feria et al, 2003;Meng & Sedgwick, 2001Ni et al, 2004Ni et al, , 2005Ni et al, , 2007Ooi et al, 2001;Sinai et al, 1998;. Future studies are needed to examine the relative influence of type of surface (ground vs. ceiling) and location in the visual field in other visual tasks, such as visual search and absolute and relative distance judgments.…”

“…Overall, they found that (1) optical contact information dominated motion parallax when only one object was presented, whereas optical contact could be outweighed by a grouping effect with multiple objects moving rigidly (Ni et al, 2005); (2) the perceived distance of an object was determined both by optical contact information and by information provided by shadow, with shadow having a greater effect, especially in moving scenes (Ni et al, 2004); and (3) the addition of occlusion information limited the range of perceived distance of an object indicated by optical contact and motion parallax (Ni et al, 2007). Sinai et al (1998) found that with a gap or a change of texture on the ground surface, perceived distance was less accurate than when the ground surface was continuous.…”

“…He, & Shimojo, 1995;cf. Sedgwick, 1986), and have examined how manipulating information on the ground surface could affect the perceived location of objects in 3-D scenes (see, e.g., Feria, Braunstein, & Andersen, 2003;Meng & Sedgwick, 2001Ni, Braunstein, & Andersen, 2004, 2007Sauer, Braunstein, Saidpour, & Andersen, 2002;Sinai, Ooi, & Z. J. He, 1998;.…”

“…Recently, Ni et al (2004Ni et al ( , 2005Ni et al ( , 2007 systematically examined the relative effectiveness of optical contact information and other cues, such as motion parallax, shadow, and occlusion, on perceived distance of objects in 3-D scenes. Overall, they found that (1) optical contact information dominated motion parallax when only one object was presented, whereas optical contact could be outweighed by a grouping effect with multiple objects moving rigidly (Ni et al, 2005); (2) the perceived distance of an object was determined both by optical contact information and by information provided by shadow, with shadow having a greater effect, especially in moving scenes (Ni et al, 2004); and (3) the addition of occlusion information limited the range of perceived distance of an object indicated by optical contact and motion parallax (Ni et al, 2007).…”

Perceptual slant induced through optical contact

“…The analysis suggested that both processes interact by cumulating their effects on variable S and that the former process (depth induction) appears to be stronger than the latter (reverse projection). Recent studies on depth vision (e.g., He, Wu, Ooi, Yarbrough, & Wu, 2004;Madison et al, 2001;Ni, Braunstein, & Andersen, 2004 have examined the interaction of processes relating to optical contact and other factors of perceptual depth, such as occlusion, shadows, and motion parallax. The comparative evaluation we made may be viewed as an item to be added to this set of results, since the depth induction process we discussed essentially involves the optical contact condition.…”