In this paper we describe a neural network-based method aimed at automatically calibrating the detector module contained in a scanner for a highresolution positron emission tomography (PET) system for small animals. The detector module is composed of crystal elements, arranged in a regular matrix and sensitive to gamma rays emitted by a radioactive source. The crystal matrix is optically couple...

Suppose that an n-by-n regular matrix pencil A − λB has n distinct eigenvalues. Then determining a defective pencil E−λF which is nearest to A−λB is widely known as Wilkinson’s problem. It is shown that the pencil E − λF can be constructed from eigenvalues and eigenvectors of A − λB when A − λB is unitarily equivalent to a diagonal pencil. Further, in such a case, it is proved that the distance...

Triangulated irregular networks (TINs) are common representations of surfaces in computational graphics. We define the dual of a TIN in a special way, based on vertex-adjacency, and show that its Hamiltonian cycle always exists and can be found efficiently. This result has applications in transmission of large graphics datasets.

In this paper, a novel hole-filling algorithm for triangular meshes is proposed. Firstly, the hole is triangulated into a set of new triangles using modified principle of minimum angle. Then the initial patching mesh is refined according to the density of vertices on boundary edges. Finally, the patching mesh is optimized via the bilateral filter to recover missed features. Experimental results...

Given a closed triangular mesh, we construct a smooth free–form surface which is described as a collection of rational tensor–product and triangular surface patches. The surface is obtained by a special manifold surface construction, which proceeds by blending together geometry functions for each vertex. The transition functions between the charts, which are associated with the vertices of the ...

We propose an improved shape matching algorithm that extends the work of Felzenszwalb [3]. In this approach, we use triangular meshes to represent deformable objects and use dynamic programming to find the optimal mapping from the source image to the target image which minimizes a new energy function. Our energy function includes a new cost term that takes into account the center of mass of an ...

Abstact Point/feature matching in 2D images has been well studied in the computer vision community. With the huge advancement in shape scanning and acquisition technology, feature matching has recently found usefulness in 3D shape matching and searching. We study the general problem of feature correspondence in 3D shapes represented by triangular meshes. This project is a survey and comparison ...

In this work we consider triangulations of point sets in the Euclidean plane, i.e., maximal straight-line crossing-free graphs on a finite set of points. Given a triangulation of a point set, an edge flip is the operation of removing one edge and adding another one, such that the resulting graph is again a triangulation. Flips are a major way of locally transforming triangular meshes. We show t...

We present a new algorithm to compute a geodesic path over a triangulated surface. Based on Sethian’s Fast Marching Method and Polthier’s straightest geodesics theory, we are able to generate an iterative process to obtain a good discrete geodesic approximation. It can handle both convex and non-convex surfaces. r 2005 Elsevier Ltd. All rights reserved.

This is the first in a series of papers where a new gradient recovery method is introduced and analyzed. It is proved that the method is superconvergent for translation invariant finite element spaces of any order. The method maintains the simplicity, efficiency, and superconvergence properties of the Zienkiewicz-Zhu patch recovery method. In addition, under uniform triangular meshes, the metho...