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Surface Reconstruction of Freeform Objects Based on Multiresolution Volumetric Method

Journal of Computing and Information Science in engineering 2003年第4期3卷 334-338页

作者： Azernikov , Sergei Miropolsky , Alex Fischer , Anath Laboratory for Computer Graphics and CAD Department of Mechanical Engineering Technion–Israel Institute of Technology Haifa Israel 32000

Recently developed 3D scanning devices are capable of capturing point clouds, as well as additional information, such as normals and texture. This paper describes a new and fast reverse engineering method for creating a 3D computerized model from data captured by such contemporary 3D scanning devices. The proposed method aggregates large-scale 3D scanned data into an extended Hierarchical Space Decomposition Model (HSDM) based on Octree data structure. This model can represent both an object’s boundary surface and its interior volume. The HSDM enables data reduction, while preserving sharp geometrical features and object topology. As a result the execution time of the reconstruction process is significantly reduced. Moreover, the proposed model naturally allows multiresolution surface reconstruction, represented by a mesh with regular properties. Based on the proposed volumetric model, the surface reconstruction process becomes more robust and stable with respect to sampling noise.

关键词： engineering graphics Noise (Sound) Topology Reverse engineering cad/CAM computer-aided design Octrees reverse engineering Algorithms octrees

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Adaptive reconstruction of freeform objects with 3D SOM neural network grids

Adaptive reconstruction of freeform objects with 3D SOM neur...

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作者： Barhak, J. Fischer, A. CMSR Laboratory for Computer Graphics and CAD Department of Mechanical Engineering Technion-Israel Institute of Technology Haifa Israel

There are several open problems that are viewed as a bottleneck in the reverse engineering process: (1) The topology is unknown;therefore, point connectivity relations are undefined. (2) The fitted surface must satisfy global and local shape preservation criteria, which are undefined explicitly. The reconstruction is based on parameterization and fitting stages. However, the above problems are influenced mainly by the parameterization. To overcome the above problems, the neural network self-organizing map (SOM) method is proposed for creating a 3D parametric grid. The main advantage of the SOM method is that it detects the orientation of the grid and the position of the sub-boundaries. Then through an adaptive process the neural network grid is converged to the sampled shape. The SOM method is applied directly on a 3D grid and avoids projection anomalies, which are common to other methods. For the surface fitting stage the random surface error correction fitting method, which is based on the SOM method, was developed and implemented. © 2002 Elsevier Science Ltd. All rights reserved.

关键词： Reverse engineering

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Topology recognition of 3D closed freeform objects based on topological graphs

Topology recognition of 3D closed freeform objects based on ...

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Pacific Conference on computer graphics and Applications

作者： D. Steiner A. Fischer CMSR Laboratory for Computer Graphics and CAD Department of Mechanical Engineering Technion-Israel Institute of Technology Haifa Israel

ISBN: (纸本)0769512275

Reverse engineering (RE) deals with an enormous number of irregular and scattered digitized points that require intensive processing in order to reconstruct the surfaces of an object. Surface reconstruction of freeform objects is based on geometrical and topological criteria. Current fitting methods reconstruct an object using a bottom-up approach, from points to a dense mesh, and finally into smoothed connected freeform sub-surfaces. This type of reconstruction, however, can cause topological problems that lead to undesired surface fitting results. Such problems are particularly common with concave shapes. To avoid problems of this type, the paper proposes a new method that automatically detects the topological structure of an object as a base for surface fitting. The topological reconstruction method described in the paper is based on two stages: (1) creating 3D non-self-intersecting iso-curves from a 3D triangular mesh and (2) extracting a topological graph. The feasibility of the proposed topological reconstruction method is demonstrated on several examples using freeform objects with complex topologies.

关键词： Topology Surface fitting Surface reconstruction Shape Reconstruction algorithms Reverse engineering Laboratories computer graphics mechanical engineering Scattering

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Adaptive reconstruction of freeform objects with 3D SOM neural network grids

Adaptive reconstruction of freeform objects with 3D SOM neur...

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Pacific Conference on computer graphics and Applications

作者： J. Barhak A. Fischer CMSR Laboratory for Computer Graphics and CAD Department of Mechanical Engineering Technion-Israel Institute of Technology Haifa Israel

Reverse engineering is an important process in cad systems today. Yet several open problems lead to a bottleneck in the reverse engineering process. First, because the topology of the object to be reconstructed is unknown, point connectivity relations are undefined. Second, the fitted surface must satisfy global and local shape preservation criteria that are undefined explicitly. In reverse engineering, object reconstruction is based both on parameterization and on fitting. Nevertheless, the above problems are influenced mainly by parameterization. In order to overcome the above problems, the paper proposes a neural network, Self Organizing Map (SOM) method, for creating a 3D parametric grid. The main advantage of the proposed SOM method is that it detects both the orientation of the grid and the position of the sub-boundaries. The neural network grid converges to the sampled shape through an adaptive learning process. The SOM method is applied directly on 3D sampled data and avoids the projection anomalies common to other methods. The paper also presents boundary correction and growing grid extensions to the SOM method. In the surface fitting stage, an RSEC (Random Surface Error Correction) fitting method based on the SOM method was developed and implemented.

关键词： Neural networks Surface fitting Reverse engineering Surface reconstruction Shape Spline Laser modes Data mining Jacobian matrices Laboratories

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mechanically based design: adaptive refinement for B-spline finite element

Mechanically based design: adaptive refinement for B-spline ...

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International Conference on Shape Modeling and Applications

作者： P. Kagan A. Fischer P. Bar-Yoseph Laboratory for Computer Graphics and CAD Mechanical Engineering Department Technion-Israel Institute of Technology Haifa Israel Computational Mechanics Laboratory Mechanical Engineering Department Technion-Israel Institute of Technology Haifa Israel

ISBN: (纸本)0769508537

This paper presents a method for adaptive refinement within an integrated mechanically based CAE system. The system uses a mechanical B-spline finite element model for both geometric design and mechanical analysis. A technique for locally refining a solution by B-spline finite elements is presented. The key component in the proposed method is the linear coordinate transformation introduced into the refined element. The transformation is constructed in such a way that the transformed nodal configuration of the refined element is identical to the nodal configuration of the neighbor elements. Therefore, the assembly proceeds in the regular fashion, while the C/sup 0/ continuity is forced along the inter-element boundary exactly. The proposed adaptive refinement method has been implemented both for surface and solid design without substantial differences in technical complexity. Its feasibility as applied to sculptured surface and solid objects is demonstrated by several examples.

关键词： Spline Finite element methods computer aided engineering Shape Laboratories Solid modeling Algorithm design and analysis computer graphics Design automation mechanical engineering

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Fairing recursive subdivision surfaces with curve interpolation constraints

Fairing recursive subdivision surfaces with curve interpolat...

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International Conference on Shape Modeling and Applications

作者： A.H. Nasri Tae-Wan Kim Kunwoo Lee Department of Mathematics and Computer Science American University of Beirut Beirut Lebanon CAD Laboratory School of Mechanical and Aerospace Engineering Seoul National University Seoul South Korea

ISBN: (纸本)0769508537

Given a polygonal mesh with a set of tagged control polygons, a subdivision surface that interpolates the B-spline curves of these control polygons can be obtained by constructing a set of polygonal complexes, each of which converges to one of the given curves. The construction process will geometrically and topologically disturb the initial and/or the subdivided polygonal meshes in the vicinity of the polygonal complexes. This may result in poorly shaped surfaces across the interpolated curves. Based on signal fairing, this paper describes a method to fair such a surface and paves the way to achieve further constraints such as interpolating curves with predefined tangent plane or cross curvature.

关键词： Interpolation Spline Refining Laboratories Mathematics computer science Aerospace engineering Centralized control computer graphics Rendering (computer graphics)

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A graphic view of linear algebra

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computer-Aided Design 2000年第4期32卷 295-295页

作者： A Fischer Technion—Israel Institute of Technology Faculty of Mechanical Engineering CMSR Laboratory for Computer Graphics and CAD Haifa Israel

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Adaptive parameterization for reconstruction of 3D freeform objects from laser-scanned data 7

Adaptive parameterization for reconstruction of 3D freeform ...

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7th Pacific Conference on computer graphics and Applications, Pacific graphics 1999

作者： Fischer, A. Manor, A. Barhak, Y. CMSR Laboratory for Computer Graphics and CAD Department of Mechanical Engineering Technion - Israel Institute of Technology Haifa32000 Israel

ISBN: (纸本)0769502938

This paper proposes a new adaptive parametrization method to overcome the problems of using laser scanners in Reverse engineering. The method is based on the following stages: (a) Detecting a 3D boundary of the parametric base surface by matching an intensity image from a CCD camera with the scanned data. (b) Adaptively reconstructing a parametric base surface with a non-self intersecting grid, based on a PDE method (c) Calculating the parametrization of the 3D sampled points. (d) Fitting the surface by applying a least square (LSQ) approximation method with boundary constraints. The feasibility of the parametrization algorithm is demonstrated on several examples using sculptured free objects. © 1999 IEEE.

关键词： Reverse engineering

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Adaptive parameterization for reconstruction of 3D freeform objects from laser-scanned data

Adaptive parameterization for reconstruction of 3D freeform ...

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Pacific Conference on computer graphics and Applications

作者： A. Fischer A. Manor Y. Barhak CMSR Laboratory for Computer Graphical and CAD Department of Mechanical Engineering Technion Israel Institute of Technology-Technion Haifa Israel

关键词： Surface fitting Surface reconstruction Image reconstruction Reverse engineering Charge coupled devices Charge-coupled image sensors Least squares approximation Approximation methods

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Training environment for inferior vena caval filter placement

Training environment for inferior vena caval filter placemen...

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6th Conferenc on Medicine Meets Virtual Reality, MMVR 1998

作者： Hahn, James K. Kaufman, Roger Winick, Adam B. Carleton, Thurston Park, Youngser Lindeman, Rob Oh, Kwang-Man Ai-Ghreimil, Nadia Walsh, Raymond J. Loew, Murray Gerber, Joanne Sankar, Siddarth Laboratory for Advanced Computer Applications in Medicine Institute for Computer Graphics George Washington University Washington DC 20052 United States Department of Electrical Engineering and Computer Science George Washington University Washington DC 20052 United States Department of Radiology George Washington University Washington DC 20052 United States Department of Civil and Mechanical Engineering George Washington University Washington DC 20052 United States Department of Anatomy and Cell Biology George Washington University Washington DC 20052 United States Institute for Medical Imaging and Image Analysis George Washington University Washington DC 20052 United States

ISBN: (纸本)9051993862

This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgical and interventional radiology procedures at the laboratory for Advanced computer Applications in Medicine at the George Washington University. In this procedure a filter is placed in the inferior vena cava to prevent blood clots from the lower portion of the body from reaching the lungs and causing a pulmonary embolus. The simulation is designed to provide both tutorial and testing modes for the filter placement procedure.

关键词： Virtual reality

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