Modeling long-range interactions across the visual field in stereo correspondence

When the eyes are converged, most objects in the visual scene will have a significant vertical disparity as measured at the retina. The pattern of vertical disparity across the retina is largely independent of object depth, depending mainly on the particular eye position adopted. Recently, Phillipson and Read (2010, European Journal of Neuroscience, doi:10.1111/j.1460-9568.2010.07454.x) showed that humans are better at achieving stereo correspondence when the vertical disparity field indicated infinite viewing distance, even when the physical viewing distance was just 30cm. They interpreted this as indicating that disparity encoding is optimized for long viewing distances, and is not updated to reflect changes in eye posture. Their results also indicated a significant effect of the visual periphery. Performance was better when the vertical disparity across the entire visual field was consistent with a given binocular eye position – even when this was not the eye position actually adopted – than when the vertical disparity beyond 20o eccentricity indicated a different eye position than that within 20o eccentricity. This is a surprising result, since (i) the task was to detect a target 8o in diameter, extending from 10o to 18o eccentricity, so information beyond 20o was completely irrelevant to the task, and (ii) many previous results indicate that the visual system detects and uses vertical disparity in local regions, even when the global vertical disparity field is not consistent with any single binocular eye position. Here, I show that this effect can be explained by a template-matching model in which the response of a population of disparity-detectors is compared with stored templates of the response expected to stimuli of known disparity

Discrete and continuous character-based disparity analyses converge to the same macroevolutionary signa. A case study from captorhinids

The relationship between diversity and disparity during the evolutionary history of a clade provides unique insights into evolutionary radiations and the biological response to bottlenecks and to extinctions. Here we present the first comprehensive comparison of diversity and disparity of captorhinids, a group of basal amniotes that is important for understanding the early evolution of high-fiber herbivory. A new fully resolved phylogeny is presented, obtained by the inclusion of 31 morphometric characters. The new dataset is used to calculate diversity and disparity through the evolutionary history of the clade, using both discrete and continuous characters. Captorhinids do not show a decoupling between diversity and disparity, and are characterized by a rather symmetric disparity distribution, with a peak in occupied morphospace at about the midpoint of the clade’s evolutionary history (Kungurian). This peak represents a delayed adaptive radiation, identified by the first appearance of several high-fiber herbivores in the clade, along with numerous omnivorous taxa. The discrete characters and continuous morphometric characters indicate the same disparity trends. Therefore, we argue that in the absence of one of these two possible proxies, the disparity obtained from just one source can be considered robust and representative of a general disparity pattern

3D image analysis for pedestrian detection

A method for solving the dense disparity stereo correspondence problem is presented in this paper. This technique is designed specifically for pedestrian detection type applications. A new Ground Control Points (GCPs) scheme is introduced, using groundplane homography information to determine regions in which good GCPs are likely to occur. The method also introduces a dynamic disparity limit constraint to further improve GCP selection and dense disparity generation. The technique is applied to a real world pedestrian detection scenario with a background modeling system based on disparity and edges

The relationship between payroll and performance disparity in major league baseball: an alternative measure

This paper introduces an alternative method of measuring competitive balance in major league baseball and employs it to assess both payroll (talent) disparity and performance (wins) disparity for 30 selected years between 1929 and 2002. Attention is devoted to the impact of two critical events in the evolution of the game: the influx of non-white players and the advent of free agency. The joint effect of these events was to increase payroll disparity while simultaneously reducing performance disparity. A single equation regression model found the effect of payroll disparity on wins disparity in the post free agency period to be positive and significant. The increasing disparity in payrolls since the mid 1990s, particularly in the American League, suggests that the luxury tax has been ineffectual and that greater performance disparity can be expected in the near future.

Relaxation Scenarios in a Mixture of Large and Small Spheres: Dependence on the Size Disparity

We present a computational investigation on the slow dynamics of a mixture of large and small soft spheres. By varying the size disparity at a moderate fixed composition different relaxation scenarios are observed for the small particles. For small disparity density-density correlators exhibit moderate stretching. Only small quantitative differences are observed between dynamic features for large and small particles. On the contrary, large disparity induces a clear time scale separation between the large and the small particles. Density-density correlators for the small particles become extremely stretched, and display logarithmic relaxation by properly tuning the temperature or the wavevector. Self-correlators decay much faster than density-density correlators. For very large size disparity, a complete separation between self- and collective dynamics is observed for the small particles. Self-correlators decay to zero at temperatures where density-density correlations are frozen. The dynamic picture obtained by varying the size disparity resembles features associated to Mode Coupling transition lines of the types B and A at, respectively, small and very large size disparity. Both lines might merge, at some intermediate disparity, at a higher-order point, to which logarithmic relaxation would be associated. This picture resembles predictions of a recent Mode Coupling Theory for fluids confined in matrixes with interconnected voids [V. Krakoviack, Phys. Rev. Lett. {\bf 94}, 065703 (2005)].Comment: Journal of Chemical Physics 125, 164507 (2006