Scale-Space Representation and Classification of 3D Models

2003 ◽  
Vol 3 (4) ◽  
pp. 315-324 ◽  
Author(s):  
Dmitriy Bespalov and ◽  
Ali Shokoufandeh ◽  
William C. Regli ◽  
Wei Sun
Keyword(s):  
Shape Matching ◽  
Distance Measure ◽  
Empirical Evaluation ◽  
3D Models ◽  
Scale Space ◽  
Space Representation ◽  
Point Distribution ◽  
Solid Models ◽  
Recent Developments

This paper presents a framework for shape matching and classification through scale-space decomposition of 3D models. The algorithm is based on recent developments in efficient hierarchical decomposition of a point distribution in metric space p,d using its spectral properties. Through spectral decomposition, we reduce the problem of matching to that of computing a mapping and distance measure between vertex-labeled rooted trees. We use a dynamic programming scheme to compute distances between trees corresponding to solid models. Empirical evaluation of the algorithm on an extensive set of 3D matching trials demonstrates both robustness and efficiency of the overall approach. Lastly, a technique for comparing shape matchers and classifiers is introduced and the scale-space method is compared with six other known shape matching algorithms.

Local Feature Extraction Using Scale-Space Decomposition

2004 ◽  
Author(s):  
Dmitriy Bespalov ◽  
Ali Shokoufandeh ◽  
William C. Regli ◽  
Wei Sun
Keyword(s):  
Feature Extraction ◽  
Distance Measure ◽  
Scale Space ◽  
Extraction Process ◽  
Decomposition Approach ◽  
Space Decomposition ◽  
Surface Triangulation ◽  
Recent Developments ◽  
Cad Models ◽  
Future Work

In our recent work we have introduced a framework for extracting features from solid of mechanical artifacts in polyhedral representation based on scale-space feature decomposition [1]. Our approach used recent developments in efficient hierarchical decomposition of metric data using its spectral properties. In that work, through spectral decomposition, we were able to reduce the problem of matching to that of computing a mapping and distance measure between vertex-labeled rooted trees. This work discusses how Scale-Space decomposition frame-work could be extended to extract features from CAD models in polyhedral representation in terms of surface triangulation. First, we give an overview of the Scale-Space decomposition approach that is used to extract these features. Second, we discuss the performance of the technique used to extract features from CAD data in polyhedral representation. Third, we show the feature extraction process on noisy data — CAD models that were constructed using a 3D scanner. Finally, we conclude with discussion of future work.

scholarly journals Point clouds segmentation as base for as-built BIM creation

2015 ◽  
Vol II-5/W3 ◽  
pp. 191-197 ◽  
Author(s):  
H. Macher ◽  
T. Landes ◽  
P. Grussenmeyer
Keyword(s):  
Point Cloud ◽  
Point Clouds ◽  
3D Models ◽  
Point Distribution ◽  
Segmentation Approach ◽  
The Creation ◽  
Future Work ◽  
Potential Use

In this paper, a three steps segmentation approach is proposed in order to create 3D models from point clouds acquired by TLS inside buildings. The three scales of segmentation are floors, rooms and planes composing the rooms. First, floor segmentation is performed based on analysis of point distribution along Z axis. Then, for each floor, room segmentation is achieved considering a slice of point cloud at ceiling level. Finally, planes are segmented for each room, and planes corresponding to ceilings and floors are identified. Results of each step are analysed and potential improvements are proposed. Based on segmented point clouds, the creation of as-built BIM is considered in a future work section. Not only the classification of planes into several categories is proposed, but the potential use of point clouds acquired outside buildings is also considered.

Reeb Graph Based Shape Retrieval for CAD

2003 ◽  
Author(s):  
Dmitriy Bespalov ◽  
William C. Regli ◽  
Ali Shokoufandeh
Keyword(s):  
Shape Matching ◽  
Scale Space ◽  
Modeling Language ◽  
Reeb Graph ◽  
Mechanical Parts ◽  
Solid Models ◽  
Cad Models ◽  
Complex Models ◽  
Reeb Graphs ◽  
Future Work

Our recent work has described a framework for matching solid of mechanical artifacts models based on scale-space feature decomposition. In this work we adopt a method of comparing solid models based on Multiresolutional Reeb Graphs (MRG) similarity computations. This method was originally proposed by Hilaga et al. in [1]. Reeb Graph technique applies MRG structure to comparisons of approximate models found in the graphics community, such as polygonal meshes, faceted representation and Virtual Reality Modeling Language (VRML) models. First, we provide a brief review of shape matching using Multiresolutional Reeb Graphs and present an approach to matching solid models. Second, we show the performance of the Reeb Graph technique when handling primitive CAD models, such as cubes and spheres; then we perform experiments with more complex models, such as LEGO models and mechanical parts, and we discuss Reeb Graph technique’s performance on complex CAD models. Third, we emphasize several problems with the existing technique. Finally, we conclude with discussion of future work.

COMPARATIVE ANALYSIS FOR THREE FIXTURES OF PAUWELLS-II BY THE BIOMECHANICAL FINITE ELEMENT METHOD

2019 ◽  
Vol 20 (01) ◽  
pp. 1950079
Author(s):  
MATTHEW JIAN-QIAO PENG ◽  
HONGWEN XU ◽  
HAI-YAN CHEN ◽  
XIANGYANG JU ◽  
YONG HU ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
Femoral Shaft ◽  
3D Models ◽  
Procedure Time ◽  
Stable Fixation ◽  
Secondary Fracture ◽  
Solid Models ◽  
Acute Correction ◽  
Hip Screw

Little is known about why and how biomechanics govern the hypothesis that three-Lag-Screw (3LS) fixation is a preferred therapeutic technique. A series models of surgical internal-fixation for femoral neck fractures of Pauwells-II will be constructed by an innovative approach of finite element so as to determine the most stable fixation by comparison of their biomechanical performance. Seventeen sets of CT scanned femora were imported onto Mimics extracting 3D models; these specimens were transferred to Geomagic Studio for a simulative osteotomy and kyrtograph; then, they underwent UG to fit simulative solid models; three sorts of internal fixators were expressed virtually by Pro-Engineer. Processed by Hypermesh, all compartments were assembled onto three systems actually as “Dynamic hip screw (DHS), 3LS and DHS+LS”. Eventually, numerical models of Finite Elemental Analysis (FEA) were exported to AnSys for solution. Three models for fixtures of Pauwells-II were established, validated and analyzed with the following findings: Femoral-shaft stress for [Formula: see text](3LS) is the least; Internal-fixator stress (MPa) for [Formula: see text]; Integral stress (MPa) for [Formula: see text]; displacement of femoral head (mm) for a[Formula: see text](DHS+LS) = 0.735; displacement of femoral shaft (mm) for [Formula: see text]; and displacement of fixators for [Formula: see text]. Mechanical comparisons for other femoral parks are insignificantly different, and these data can be abstracted as follows: the stress of 3LS-system was checked to be the least, and an interfragmentary displacement of DHS+LS assemblages was assessed to be the least”. A 3LS-system should be recommended to clinically optimize a Pauwells-II facture; if treated by this therapeutic fixation, breakage of fixators or secondary fracture is supposed to occur rarely. The strength of this study is that it was performed by a computer-aided simulation, allowing for design of a preoperative strategy that could provide acute correction and decrease procedure time, without harming to humans or animals.

Automated classification of human lung sound signals using phase space representation of intrinsic mode function

2021 ◽  
Author(s):  
Sibghatullah I. Khan ◽  
Vikram Palodiya ◽  
Lavanya Poluboyina
Keyword(s):  
Phase Space ◽  
Human Lung ◽  
Feature Space ◽  
Normal Lung ◽  
Space Representation ◽  
Support Vector ◽  
Lung Sounds ◽  
Lung Sound ◽  
Phase Space Representation

Abstract Bronchiectasis and chronic obstructive pulmonary disease (COPD) are common human lung diseases. In general, the expert pulmonologistcarries preliminary screening and detection of these lung abnormalities by listening to the adventitious lung sounds. The present paper is an attempt towards the automatic detection of adventitious lung sounds ofBronchiectasis,COPD from normal lung sounds of healthy subjects. For classification of the lung sounds into a normaland adventitious category, we obtain features from phase space representation (PSR). At first, the empirical mode decomposition (EMD) is applied to lung sound signals to obtain intrinsic mode functions (IMFs). The IMFs are then further processed to construct two dimensional (2D) and three dimensional (3D) PSR. The feature space includes the 95% confidence ellipse area and interquartile range (IQR) of Euclidian distances computed from 2D and 3D PSRs, respectively. The process is carried out for the first four IMFs correspondings to normal and adventitious lung sound signals. The computed features depicta significant ability to discriminate the two categories of lung sound signals.To perform classification, we use the least square support vector machine with two kernels, namely, polynomial and radial basis function (RBF).Simulation outcomes on ICBHI 2017 lung sound dataset show the ability of the proposed method in effectively classifying normal and adventitious lung sound signals. LS-SVM is employing RBF kernel provides the highest classification accuracy of 97.67 % over feature space constituted by first, second, and fourth IMF.

scholarly journals Comparative Analysis for Internal Fixations of Pauwels II by Biomechanical Finite Element Method

2019 ◽  
Vol 103 (9-10) ◽  
pp. 493-504
Author(s):  
Matthew Jian-Qiao Peng ◽  
Xiangyang Ju ◽  
Hai-Yan Chen ◽  
Bai Bo ◽  
XinXu Li
Keyword(s):  
Finite Element ◽  
South Carolina ◽  
Femoral Neck ◽  
Femoral Neck Fracture ◽  
3D Models ◽  
Secondary Fracture ◽  
Solid Models ◽  
Neck Fracture ◽  
Hip Screw ◽  
3D Solid

Purpose: A series models of surgical internal fixation for femoral neck fracture of Pauwels II will be constructed by an innovative approach of finite element so as to determine the most stable fixation by comparison of their biomechanical performance. Method: Seventeen specimens of proximal femurs scanned by computed tomography in Digital Imaging and Communications in Medicine (DICOM) format were input onto Mimics rebuilding 3D models; their stereolithography (STL) format dataset were imported into Geomagic Studio (3D Systems, Rock Hill, South Carolina) for simulative osteotomy and non-uniform rational basis spline kartograph; the generated IGS dataset were interacted by UG to fit simulative 3D-solid models; 3 sorts of internal fixators were expressed in 3D model by ProE (PTC, Boston, Connecticut) program virtually. Processed by HyperMesh (Altair, Troy, Michigan), all compartments (fracture model + internal immobilization) were assembled onto 3 systems actually as: Dynamic hip screw (DHS) / Lag screw (LS) / DHS+LS. Eventually, a numerical model of finite elemental analysis was exported to ANSYS for solution. Result: Three models of internal fixations for femoral neck fracture of Pauwels II were established and validated effectively, the stress and displacement of each internal pin were analyzed, the advantages of each surgical therapy for femoral neck fracture of Pauwels II were compared and demonstrated synthetically as: “The contact stress of 3-LS-system was checked to be the least; the interfragmentary displacement of DHS+1-LS assemblages was assessed to be the least.” Conclusion: 3-LS-system is recommended to be a clinical optimization for Pauwels II femoral neck facture, by this therapeutic fixation mechanically, breakage of fixators, or secondary fracture rarely occurs.

A NEW FORMULATION OF QUANTUM FIELD THEORY ON S4

1994 ◽  
Vol 09 (18) ◽  
pp. 3245-3282 ◽  
Author(s):  
B.A. HARRIS ◽  
G.C. JOSHI
Keyword(s):  
Field Theory ◽  
Angular Momentum ◽  
Quantum Gravity ◽  
Momentum Space ◽  
Space Representation ◽  
Fundamental Constants ◽  
Spherical Space ◽  
Recent Developments ◽  
New Formulation ◽  
Constants Of Nature

Recent developments in quantum gravity suggest that wormholes may influence the observed values of the constants of nature. The Euclidean formulation of quantum gravity predicts that wormholes induce a probability distribution in the space of possible fundamental constants. In particular, the effective action on a large spherical space may lead to the vanishing of the cosmological constant and possibly determine the values of other constants of nature. The ability to perform calculations involving interacting quantum fields, particularly non-Abelian models, on a four-sphere is vital if one is to investigate this possibility. In this paper we present a new formulation of field theory on a four-sphere using the angular momentum space representation of SO(5). We give a review of field theory on a sphere and then show how a matrix element prescription in angular momentum space and a new summation technique based on the complex l plane, overcome previous limitations in calculational techniques. The standard one-loop graphs of QED are given as examples.

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