scholarly journals Surface Mesh Discrete Curvature Estimators

2008 ◽  
Author(s):  
Arnaud Gelas ◽  
Alexandre Gouaillard ◽  
Sean Megason
Keyword(s):  
Data Structure ◽  
Shape Analysis ◽  
Smooth Surface ◽  
Surface Mesh ◽  
Surface Evolution ◽  
Discrete Curvature ◽  
Analytical Expression ◽  
Surface Segmentation

Computing local curvatures of a given surface is important for applications, shape analysis, surface segmentation, meshing, and surface evolution. For a given smooth surface (with a given analytical expression which is sufficiently differentiable) curvatures can be analytically and directly computed. However in real applications, one often deals with a surface mesh which is an insufficiently differentiable approximation, and thus curvatures must be estimated. Based on a surface mesh data structure (~), we introduce and implement curvature estimators following the approach of Meyer. We show on a sphere that this method results in more stable curvature approximations than the commonly used discrete estimators (as used in VTK: ).

scholarly journals Surface Mesh Normals Filter

2008 ◽  
Author(s):  
Arnaud Gelas ◽  
Alexandre Gouaillard ◽  
Sean Megason
Keyword(s):  
Data Structure ◽  
Surface Mesh ◽  
Triangular Surface Mesh

We have previously developed a new surface mesh data structure in itk (~). In this document we describe a new filter () to estimate normals for a given triangular surface mesh in this data structure. Here we describe the implementation and use of this filter for calculating normals of a .

scholarly journals Surface Meshes Incremental Decimation Framework

2008 ◽  
Author(s):  
Arnaud Gelas ◽  
Alexandre Gouaillard ◽  
Sean Megason
Keyword(s):  
Data Structure ◽  
General Framework ◽  
Computational Time ◽  
Surface Mesh ◽  
Surface Meshes ◽  
Mesh Decimation ◽  
Vertex Removal ◽  
Edge Collapse

When dealing with meshes, it is often preferable to work with a lower resolution mesh for computational time purpose, display. The process of reducing a given mesh, mesh decimation, is thus an important step in most of pipeline dealing with meshes. Incremental decimation algorithms, the most popular ones, consists of iteratively removing one point of the mesh, by Euler operations such as vertex removal or edge collapse. Here we focus on edge collapse based decimation approaches and propose a general framework based on a surface mesh data structure (itk::QuadEdgeMesh [3]). Our implementation intends to be as general and as flexible as possible. Indeed it can theoretically be applied on any polygonal mesh1; the measure, functional to be optimized at each iteration, the objective to be reached, and optional methods like point relocation to enhance the geometry of the resulting mesh, are given by the user. We provide here two specific implementations: itk::QuadEdgeMeshSquaredEdgeLengthDecimation and itk::QuadEdgeMeshQuadricDecimation, that could be used as example to implement additional algorithms.

Surface mesh segmentation and smooth surface extraction through region growing

2005 ◽  
Vol 22 (8) ◽  
pp. 771-792 ◽  
Author(s):  
Miguel Vieira ◽  
Kenji Shimada
Keyword(s):  
Smooth Surface ◽  
Region Growing ◽  
Mesh Segmentation ◽  
Surface Mesh ◽  
Surface Extraction

On the influence of specimen thickness in TEM images of super-conducting vortices

1996 ◽  
Vol 54 ◽  
pp. 724-725
Author(s):  
J. Bonevich ◽  
D. Capacci ◽  
G. Pozzi ◽  
K. Harada ◽  
H. Kasai ◽  
...  
Keyword(s):  
Flux Line ◽  
Analytical Form ◽  
Realistic Model ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Flux Tubes ◽  
Analytical Expression ◽  
Flux Lines ◽  
Normal Core ◽  
Two Parameters

The successful observation of superconducting flux lines (fluxons) in thin specimens both in conventional and high Tc superconductors by means of Lorentz and electron holography methods has presented several problems concerning the interpretation of the experimental results. The first approach has been to model the fluxon as a bundle of flux tubes perpendicular to the specimen surface (for which the electron optical phase shift has been found in analytical form) with a magnetic flux distribution given by the London model, which corresponds to a flux line having an infinitely small normal core. In addition to being described by an analytical expression, this model has the advantage that a single parameter, the London penetration depth, completely characterizes the superconducting fluxon. The obtained results have shown that the most relevant features of the experimental data are well interpreted by this model. However, Clem has proposed another more realistic model for the fluxon core that removes the unphysical limitation of the infinitely small normal core and has the advantage of being described by an analytical expression depending on two parameters (the coherence length and the London depth).

Three-Dimensional Structure of Rotavirus-Fab Complex

1990 ◽  
Vol 48 (1) ◽  
pp. 238-239
Author(s):  
B.V.V. Prasad ◽  
E. Marietta ◽  
J.W. Burns ◽  
M.K. Estes ◽  
W. Chiu
Keyword(s):  
Image Processing ◽  
Smooth Surface ◽  
Three Dimensional ◽  
Outer Shell ◽  
Dimensional Structure ◽  
Structural Studies ◽  
Cell Penetration ◽  
Electron Cryomicroscopy ◽  
Image Processing Techniques ◽  
Processing Techniques

Rotaviruses are spherical, double-shelled particles. They have been identified as a major cause of infantile gastroenteritis worldwide. In our earlier studies we determined the three-dimensional structures of double-and single-shelled simian rotavirus embedded in vitreous ice using electron cryomicroscopy and image processing techniques to a resolution of 40Å. A distinctive feature of the rotavirus structure is the presence of 132 large channels spanning across both the shells at all 5- and 6-coordinated positions of a T=13ℓ icosahedral lattice. The outer shell has 60 spikes emanating from its relatively smooth surface. The inner shell, in contrast, exhibits a bristly surface made of 260 morphological units at all local and strict 3-fold axes (Fig.l).The outer shell of rotavirus is made up of two proteins, VP4 and VP7. VP7, a glycoprotein and a neutralization antigen, is the major component. VP4 has been implicated in several important functions such as cell penetration, hemagglutination, neutralization and virulence. From our earlier studies we had proposed that the spikes correspond to VP4 and the rest of the surface is composed of VP7. Our recent structural studies, using the same techniques, with monoclonal antibodies specific to VP4 have established that surface spikes are made up of VP4.

Contrast From Point Defects in The Infinitesimal Approximation

1980 ◽  
Vol 38 ◽  
pp. 350-351
Author(s):  
L. J. Sykes ◽  
J. J. Hren
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Broad Class ◽  
Stacking Fault ◽  
Crystalline Solids ◽  
Dislocation Loops ◽  
Analytical Expression ◽  
Stacking Fault Tetrahedra

In electron microscope studies of crystalline solids there is a broad class of very small objects which are imaged primarily by strain contrast. Typical examples include: dislocation loops, precipitates, stacking fault tetrahedra and voids. Such objects are very difficult to identify and measure because of the sensitivity of their image to a host of variables and a similarity in their images. A number of attempts have been made to publish contrast rules to help the microscopist sort out certain subclasses of such defects. For example, Ashby and Brown (1963) described semi-quantitative rules to understand small precipitates. Eyre et al. (1979) published a catalog of images for BCC dislocation loops. Katerbau (1976) described an analytical expression to help understand contrast from small defects. There are other publications as well.

A Data Structure for Disjoint Sets

Genomic Perl ◽  
2002 ◽  
pp. 313-317
Keyword(s):  
Data Structure ◽  
Disjoint Sets

Latent psychological data structure of secondary driving tasks

2004 ◽  
Author(s):  
Reates Curry
Keyword(s):  
Data Structure ◽  
Psychological Data
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