The cortical processing of illusory contours provides a unique window for exploring the brain mechanisms underlying visual perception. Previous electrophysiological single-cell recordings demonstrate that a subgroup of cells in macaque V1 and V2 signal the presence of illusory contours, whereas recent human brain imaging studies reveal higher-order visual cortices playing a central role in illu...

We study the Glauber dynamics for the (2+1)d Solid-On-Solid model above a hard wall and below a far away ceiling, on an L × L box of Z with zero boundary conditions, at large inverse-temperature β. It was shown by Bricmont, El-Mellouki and Fröhlich [12] that the floor constraint induces an entropic repulsion effect which lifts the surface to an average height H ≍ (1/β) logL. As an essential ste...

A pentagon in the plane with fixed side-lengths has a two-dimensional shape space. Considering the pentagon as a mechanical system with point masses at the corners we answer the question of how much the pentagon can rotate with zero angular momentum. We show that the shape space of the equilateral pentagon has genus 4 and find a fundamental region by discrete symmetry reduction with respect to ...

The spatial relationships of contours play important roles in many areas such as extracting topographic features from contour maps, automatically identifying elevations of scanned contours, et al.. In those areas, one key issue is making computers identify the relationships of contours. The spatial relationships of contours are usually represented by contour tree. Contour tree is essentially a ...

In this paper, we propose an Expectation-Maximization (EM) approach to separate a shape database into different shape classes, while simultaneously estimating the shape contours that best exemplify each of the different shape classes. We begin our formulation by employing the level set function as the shape descriptor. Next, for each shape class we assume that there exists an unknown underlying...

We introduce a very fast and reliable method for shape similarity retrieval in large image databases which is robust with respect to noise, scale and orientation changes of the objects. The maxima of curvature zero crossing contours of Curvature Scale Space (CSS) image are used to represent the shapes of object boundary contours. While a complex boundary is represented by about ve pairs of inte...

Previous experimental studies have provided evidence that closed contours are easier to detect than open contours in random-element displays, and previous theoretical studies have shown that these effects might be explained by an active neural mechanism (e.g., a "reverberating neural circuit") sensitive to closure. To test this hypothesis, detection thresholds were measured in five experiments ...

Overlaid plots of iso-contours in individual members of a scalar ensemble field are a popular concept to visualize the data uncertainty. However, such plots do not allow concluding on the spatial cumulative probability distribution of the iso-contours, and they cannot reveal distribution characteristics like spread and topology for huge amounts of contours. In this paper, we propose a new visua...