Echo planar imaging (EPI) suffers from geometric distortions caused by magnetic field inhomogeneities, which can be time-varying as a result of small amounts of head motion that occur over seconds and minutes during fMRI experiments, also known as "dynamic geometric distortion". Phase Labeling for Additional Coordinate Encoding (PLACE) is a promising technique for geometric distortion correctio...

Evaluating the visibility threshold for a local geometric distortion on a 3D mesh and its applications Geometric operations applied to a 3D mesh introduce geometric distortion in the form of vertex displacement that can be visible to a human observer. In this thesis, we have studied the perceptual impact of these geometric distortions. More precisely, our goal is to compute the threshold beyond...

A new method is proposed for removing geometric distortion in images of submerged objects observed from outside shallow water. The water waves will affect the appearance of the individual video frames such that no single frame is completely free of geometric distortion. This suggests that, in principle, it is possible to perform a selection of a set of low distortion sub-regions from each video...

The matching of point sets that are characterized only by their geometric configuration is a challenging problem. In this paper, we present a novel point registration algorithm for robustly identifying objects represented by two dimensional point clouds under affine distortions. We make no assumptions about the initial orientation of the point clouds and only incorporate the geometric configura...

Introduction Echo-planar imaging (EPI) is a group of fast data acquisition methods commonly used in fMRI studies. It acquires multiple image lines in k-space after a single excitation, which leads to a very short scan time. A well-known problem with EPI is that it is more sensitive to distortions due to the used encoding scheme. Source of distortion is inhomogeneity in the static B0 field that ...

Geometric distortion caused by B0 inhomogeneity is one of the most important problems for diffusion-weighted images (DWI) using single-shot, echo planar imaging (SS-EPI). In this study, large-deformation, diffeomorphic metric mapping (LDDMM) algorithm has been tested for the correction of geometric distortion in diffusion tensor images (DTI). Based on data from nine normal subjects, the amount ...