• Title/Summary/Keyword: Subdivision Modeling

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Development of an Algorithm Preserving Sharp-Edges of Control Meshes in the Doo-Sabin Subdivision Scheme (조정 메쉬의 각진 모서리를 유지하기 위한 수정 Doo-Sabin 곡면 분할 알고리듬 개발)

  • 이현찬;주병준;홍충성
    • Korean Journal of Computational Design and Engineering
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    • v.8 no.1
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    • pp.1-9
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    • 2003
  • Recently, designing 3D objects using various modeling techniques become getting more important issues in related industrial fields. The subdivision scheme is a technique that generates a smooth sur-face through many times of refinement processes that split polygons of control mesh into several smaller polygons. In this paper, we propose a new subdivision algorithm that preserves sharp-edges of control mesh after several refinement processes in the Doo-Sabin subdivision scheme. Using the pro-posed algorithm, the Doo-Sabin subdivision scheme can be well applied to modeling 3D objects with sharp-edges.

Inscribed Approximation based Adaptive Tessellation of Catmull-Clark Subdivision Surfaces

  • Lai, Shuhua;Cheng, Fuhua(Frank)
    • International Journal of CAD/CAM
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    • v.6 no.1
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    • pp.139-148
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    • 2006
  • Catmull-Clark subdivision scheme provides a powerful method for building smooth and complex surfaces. But the number of faces in the uniformly refined meshes increases exponentially with respect to subdivision depth. Adaptive tessellation reduces the number of faces needed to yield a smooth approximation to the limit surface and, consequently, makes the rendering process more efficient. In this paper, we present a new adaptive tessellation method for general Catmull-Clark subdivision surfaces. Different from previous control mesh refinement based approaches, which generate approximate meshes that usually do not interpolate the limit surface, the new method is based on direct evaluation of the limit surface to generate an inscribed polyhedron of the limit surface. With explicit evaluation of general Catmull-Clark subdivision surfaces becoming available, the new adaptive tessellation method can precisely measure error for every point of the limit surface. Hence, it has complete control of the accuracy of the tessellation result. Cracks are avoided by using a recursive color marking process to ensure that adjacent patches or subpatches use the same limit surface points in the construction of the shared boundary. The new method performs limit surface evaluation only at points that are needed for the final rendering process. Therefore it is very fast and memory efficient. The new method is presented for the general Catmull-Clark subdivision scheme. But it can be used for any subdivision scheme that has an explicit evaluation method for its limit surface.

A Study on approximating subdivision method considering extraordinary points (특이점의 분할을 고려한 근사 서브디비전 방법에 대한 연구)

  • 서흥석;조맹효
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.253-260
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    • 2003
  • In computer-aided geometric modeling(CAGD), subdivision surfaces are frequently employed to construct free-form surfaces. In the present study, Loop scheme and Catmull-Clark scheme are applied to generate smooth surfaces. To be consistent with the limit points of target surface, the initial sampling points are properly rearranged. The pointwise errors of curvature and position in the sequence of subdivision process are evaluated in both Loop scheme & Catmull-Clark subdivision scheme. In partcural, a general subdivision method in order to generate considering extraordinary points are implemented free from surface with arbitrary sampling point information.

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A Controllable Ternary Interpolatory Subdivision Scheme

  • Zheng, Hongchan;Ye, Zhenglin;Chen, Zuoping;Zhao, Hongxing
    • International Journal of CAD/CAM
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    • v.5 no.1
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    • pp.29-38
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    • 2005
  • A non-uniform 3-point ternary interpolatory subdivision scheme with variable subdivision weights is introduced. Its support is computed. The $C^0$ and $C^1$ convergence analysis are presented. To elevate its controllability, a modified edition is proposed. For every initial control point on the initial control polygon a shape weight is introduced. These weights can be used to control the shape of the corresponding subdivision curve easily and purposefully. The role of the initial shape weight is analyzed theoretically. The application of the presented schemes in designing smooth interpolatory curves and surfaces is discussed. In contrast to most conventional interpolatory subdivision scheme, the presented subdivision schemes have better locality. They can be used to generate $C^0$ or $C^1$ interpolatory subdivision curves or surfaces and control their shapes wholly or locally.

A New Conception in Constructive Branching Structures and Leaves using L-system

  • Abd El-Latif, Yasser M.
    • Journal of Computing Science and Engineering
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    • v.4 no.3
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    • pp.240-252
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    • 2010
  • One of the important open problems in modeling plants is the extension of subdivision algorithms to branching structures. Most of the applications use the concept of L-system to produce branching structures as a sequence of lines and apply the subdivision scheme to appear as curves. In this paper, we explain how L-systems can be modified to produce branching structures. This is also very useful for generating the geometry of various shapes. The proposed technique, called an adaptive L-System, describes branching forms and leaves by making local curve without applying the subdivision steps. Advantages of the suggested algorithm over previous techniques are given. Validation of the algorithm are discussed, analyzed and illustrated by some experimental results.

Development of Delaunay Triangulation Algorithm Using Subdivision (분할 Delaunay 삼각화 알고리즘 개발)

  • 박시형;이성수
    • Korean Journal of Computational Design and Engineering
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    • v.7 no.4
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    • pp.248-253
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    • 2002
  • Delaunay triangulation is well balanced in the sense that the triangles tend toward equiangularity. And so, Delaunay triangulation hasn't some slivers triangle. It's commonly used in various field of CAD applications, such as reverse engineering, shape reconstruction, solid modeling and volume rendering. For Example, In this paper, an improved Delaunay triangulation is proposed in 2-dimensions. The suggested algorithm subdivides a uniform grids into sub-quad grids, and so efficient where points are nonuniform distribution. To get the mate from quad-subdivision algorithm, the area where triangulation-patch will be most likely created should be searched first.

Study on approximating subdivision schemes for the application to CAD/CAE (CAD/CAE 적응을 위한 근사 서브디비전 방법의 고찰)

  • 서홍석;조맹효
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.237-243
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    • 2002
  • Recently, in computer-aided geometric modeling(CAGD), subdivision surfaces are frequently employed to construct free-form surface. Subdivision schemes have been very popular in computer graphics and animation community, but the community of CAGD adopts this tool only recently to handle surface geometry. In the present study, Loop scheme and Catmull-Clark scheme are applied to generate smooth surfaces. To be consistent with the limit points of target surface, the initial sampling points are properly rearranged. The pointwise curvature errors and coordinate value errors between the points in the sequence of subdivision process and the points on the target surface are evaluated In the numerical examples in both Loop scheme & Catmull-Clark subdivision scheme.

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Development of Delaunay triangulation algorithm using quad subdivision (Quad-Subdivision을 이용한 Delaunay 삼각화 알고리즘 개발)

  • 박시형;이성수
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.10a
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    • pp.151-156
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    • 2000
  • Delaunay triangulation is well balanced in the sense that the triangles tend toward equiangularity. And so, Delaunay triangulation hasn't some slivers triangle. It's commonly used in various field of CAD applications, such as shape reconstruction, solid modeling and volume rendering. In this paper, an improved Delaunay triangulation is proposed in 2-dimensions. The suggested algorithm subdivides a uniform grids into sub-quad grids, and so efficient where points are non-uniform distribution. To get the mate from quad-subdivision algorithm, the area where triangulation-patch will be most likely created should be searched first.

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