The geometry of the occluding contour and its effect on motion interpretation.

Form information related to occlusion is needed to correctly interpret image motion. This work describes one of a series of investigations into the form constraints on motion perception. In the present study, we focus specifically on the geometry of the occluding contour, and in particular on whether its influence on motion can be accounted for merely by its effect on perceived occlusion. We used an occluded square moving in a circle, holding the T-junctions at points of occlusion constant while manipulating the occluding contour. We found evidence for two main influences of occluding contour geometry on motion interpretation and occlusion: the convexity of the occluding contour and additional static T-junctions that are formed elsewhere on the occluding contour. Our results suggest that convex occluding contours are more occlusive than concave ones, and that T-junctions along the contour increase or decrease the strength of occlusion depending on their orientation. Motion interpretation is influenced by both factors, but their effect on motion appears to be dominated by interactions occurring at an intermediate "semilocal" scale, which is larger than the scale at which junctions are defined, but smaller than the scale of the whole moving figure. We propose that these computations are related to occlusion but are not identical to the computations that mediate static occlusion judgments.

[1]  T. Troscianko,et al.  AI and the eye , 1990 .

[2]  S. Wuerger,et al.  Perception of Moving Lines: Interactions Between Local Perpendicular Signals and 2D Motion Signals , 1997, Vision Research.

[3]  E H Adelson,et al.  Beyond Junctions: Nonlocal form Constraints on Motion Interpretation , 2001, Perception.

[4]  P Bressan,et al.  The Role of Depth Stratification in the Solution of the Aperture Problem , 1993, Perception.

[5]  Hans Wallach.  Über visuell wahrgenommene Bewegungsrichtung , 1935 .

[6]  Nava Rubin,et al.  Measuring convexity for figure/ground separation , 1999, Proceedings of the Seventh IEEE International Conference on Computer Vision.

[7]  James Elder,et al.  The effect of contour closure on the rapid discrimination of two-dimensional shapes , 1993, Vision Research.

[8]  Christopher C. Pack,et al.  The role of terminators and occlusion cues in motion integration and segmentation: a neural network model , 1999, Vision Research.

[9]  J Lorenceau,et al.  Cooperative and competitive spatial interactions in motion integration , 1999, Visual Neuroscience.

[10]  B L Anderson,et al.  Reciprocal interactions between occlusion and motion computations. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[11]  K. Nakayama,et al.  The aperture problem—II. Spatial integration of velocity information along contours , 1988, Vision Research.

[12]  M. Shiffrar,et al.  Increased Motion Linking Across Edges with Decreased Luminance Contrast, Edge Width and Duration , 1996, Vision Research.

[13]  T. D. Albright,et al.  Transparency and coherence in human motion perception , 1990, Nature.

[14]  T. Sejnowski,et al.  A selection model for motion processing in area MT of primates , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[15]  E. Adelson,et al.  Phenomenal coherence of moving visual patterns , 1982, Nature.

[16]  E H Adelson,et al.  Adventures with Gelatinous Ellipses—Constraints on Models of Human Motion Analysis , 2000, Perception.

[17]  Maggie Shiffrar,et al.  Motion integration across differing image features , 1995, Vision Research.

[18]  P. Bressan,et al.  Occlusion and the perception of coherent motion , 1991, Vision Research.

[19]  Thomas D. Albright,et al.  The interpretation of visual motion: Evidence for surface segmentation mechanisms , 1996, Vision Research.

[20]  Josh H. McDermott,et al.  Psychophysics with junctions in real images. , 2010, Perception.

[21]  N Rubin,et al.  The Role of Junctions in Surface Completion and Contour Matching , 2001, Perception.

[22]  John C. Trueswell,et al.  Surface segmentation mechanisms and motion perception , 1993, Vision Research.

[23]  Maggie Shiffrar,et al.  The influence of terminators on motion integration across space , 1992, Vision Research.

[24]  J. Todd,et al.  On the relative contributions of motion energy and transparency to the perception of moving plaids , 1996, Vision Research.

[25]  Ennio Mingolla,et al.  Monocular occlusion cues alter the influence of terminator motion in the barber pole phenomenon , 1998, Vision Research.

[26]  A. Brookes,et al.  The Concave Cusp as a Determiner of Figure—Ground , 1988, Perception.

[27]  Edward H Adelson,et al.  Junctions and cost functions in motion interpretation. , 2004, Journal of vision.

[28]  T. Albright,et al.  Luminance contrast affects motion coherency in plaid patterns by acting as a depth-from-occlusion cue , 1998, Vision Research.