In order to effectively solve the problems of global discrete grid in spatial data management and operations, a novel equal area quad-tree global discrete grid subdivision model based on latitude and longitude lines is proposed in this paper. Coding rules of grid cells, and geometric distortion calculation and analysis of the grid model are also given in the detailed subdivision process. The re...

Geometric distortion, signal-loss, and image-blurring artifacts in echo planar imaging (EPI) are caused by frequency shifts and T(2)(*) relaxation distortion of the MR signal along the k-space trajectory due to magnetic field inhomogeneities. The EPI geometric-distortion artifact associated with frequency shift can be reduced with parallel imaging techniques such as SENSE, while the signal-loss...

We present a novel approach for embedding general metric and nonmetric spaces into lowdimensional Euclidean spaces. As opposed to traditional multidimensional scaling techniques, which minimize the distortion of pairwise distances, our embedding algorithm seeks a low-dimensional representation of the data that preserves the structure (geometry) of the original data. The algorithm uses a hybrid ...

Small gradient fields resulting from incompletely canceled eddy currents can cause geometric distortion in echo-planar images. Although this distortion is negligible in most echoplanar applications, the large gradient pulses used in diffusion-weighted echo-planar imaging can result in significant image distortion. In this report, it is shown that this distortion can be significantly reduced by ...

Using an incorrect lens, or camera shake can cause the perspective of photographs to be tilted or skewed. The perspective may be distorted, and is more evident in photographs containing continuous vertical lines or geometric shapes. This paper deals with perspective distortion together with skew distortion rectification of a document image file to make its content more easily comprehendible for...

The perceptual impact of the geometric distortions introduced by the multiresolution version of the C-LPCD model is evaluated by means of psychovisual experiments. Specifically, the maximum admissible distortion that can be applied before the distortion becomes visible is measured leading to the definition of the perceptually admissible subset of C-LPCD distortions. A similar analysis is perfor...

The perceptual impact of the geometric distortions introduced by the multiresolution version of the C-LPCD model is evaluated by means of psychovisual experiments. Specifically, the maximum admissible distortion that can be applied before the distortion becomes visible is measured leading to the definition of the perceptually admissible subset of C-LPCD distortions. A similar analysis is perfor...

We propose a pose-dependent image-based rendering approach for the visualization of clothes with very high rendering quality. Our representation combines body-pose-dependent geometry and appearance. A geometric model accounts for low-resolution shape adaptation, e.g. animation and view interpolation, while small details as well as complex shading/reflection properties are accounted for through ...

A distortion theory is developed for S−unimodal maps. It will be used to get some geometric understanding of invariant Cantor sets. In particular attracting Cantor sets turn out to have Lebesgue measure zero. Furthermore the ergodic behavior of S−unimodal maps is classified according to a distortion property, called the Markov-property.

In this paper, we present our efforts towards deriving vocal tract shapes from ElectroMagnetic Articulograph data (EMA) via geometric adaptation and matching. We describe a novel approach for adapting Maeda’s geometric model of the vocal tract to one speaker in the MOCHA database. We show how we can rely solely on the EMA data for adaptation. We present our search technique for the vocal tract ...