• Title/Summary/Keyword: 3D meshes

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Wavelet-based Level-of-Detail Virtual Object Representation System (Wavelet 기반 LOD 가상객체 표현 시스템)

  • Kim, Gi-Ho;Yu, Hwang-Bin
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.3
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    • pp.766-775
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    • 2000
  • Representing 3-D objects with LOD requires a set of appropriate meshes according to the detail requirements. We have developed a system for improved geometry model data transmission and management by having only the wavelet coefficienets of the model corresponding to the detail levels, instead of generation all the meshes through wavelet transformation, when generating multiresolution meshes.

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High-quality Texture Extraction for Point Clouds Reconstructed from RGB-D Images (RGB-D 영상으로 복원한 점 집합을 위한 고화질 텍스쳐 추출)

  • Seo, Woong;Park, Sang Uk;Ihm, Insung
    • Journal of the Korea Computer Graphics Society
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    • v.24 no.3
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    • pp.61-71
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    • 2018
  • When triangular meshes are generated from the point clouds in global space reconstructed through camera pose estimation against captured RGB-D streams, the quality of the resulting meshes improves as more triangles are hired. However, for 3D reconstructed models beyond some size threshold, they become to suffer from the ugly-looking artefacts due to the insufficient precision of RGB-D sensors as well as significant burdens in memory requirement and rendering cost. In this paper, for the generation of 3D models appropriate for real-time applications, we propose an effective technique that extracts high-quality textures for moderate-sized meshes from the captured colors associated with the reconstructed point sets. In particular, we show that via a simple method based on the mapping between the 3D global space resulting from the camera pose estimation and the 2D texture space, textures can be generated effectively for the 3D models reconstructed from captured RGB-D image streams.

DEVELOPMENT OF AN HIGH-ORDER IMPLICIT DISCONTINUOUS GALERKIN METHOD ON UNSTRUCTURED MESHES (비정렬 격자계에서 고차 정확도의 내재적 불연속 갤러킨 기법의 개발)

  • Lee, H.D.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.12 no.3
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    • pp.29-40
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    • 2007
  • An implicit discontinuous Galerkin method for the two-dimensional Euler equations was developed on unstructured triangular meshes. The method can achieve high-order spatial accuracy by using hierachical basis functions based on Legendre polynomials. Numerical tests were conducted to estimate the convergence order of numerical solutions to the Ringleb flow and the supersonic vortex flow for which analytic solutions are available. Also, the flows around a 2-D circular cylinder and an NACA0012 airfoil were numerically simulated. The numerical results showed that the implicit discontinuous Galerkin methods couples with a high-order representation of curved solid boundaries can be an efficient method to obtain very accurate numerical solutions on unstructured meshes.

Automatic Generation of 3-D Finite Element Meshes: Part(II) -Mesh Generation from Tetrahedron-based Octree- (삼차원 유한요소의 자동생성 (2) -사면체 옥트리로부터의 유한요소 생성-)

  • 정융호;이건우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.3
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    • pp.647-660
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    • 1995
  • Given the tetrahedron-based octree approximation of a solid as described in part(I) of this thesis, in this part(II) a systematic procedure of 'boundary moving' is developed for the fully automatic generation of 3D finite element meshes. The algorithm moves some vertices of the octants near the boundary onto the exact surface of a solid without transforming the topology of octree leaf elements. As a result, the inner octree leaf elements can be used as exact tetrahedral finite element meshes. In addition, as a quality measure of a tetrahedral element, 'shape value' is propopsed and used for the generation of better finite elements during the boundary moving process.

Automatic Generation of Triangular Ginite Element Meshes on Three-Dimensional Surfaces (3차원 곡면에서 삼각형 유한요소망의 자동생성)

  • 채수원;손창현
    • Korean Journal of Computational Design and Engineering
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    • v.1 no.3
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    • pp.224-233
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    • 1996
  • An automatic mesh generation scheme with triangular finite elements on three-dimensional surfaces has been developed. The surface triangulation process is performed as follows. To begin, surfaces with key nodes are transformed to two-dimensional planes and the meshes with triangular elements are constructed in these planes. Finally, the constructed meshes are transformed back to the original 3D surfaces. For the mesh generation, an irregular mesh generation scheme is employed in which local mesh densities are assigned by the user along the boundaries of the analysis domain. For this purpose a looping algorithm combined with an advancing front technique using basic operators has been developed, in which the loops are recursively subdivided into subloops with the use of the best split lines and then the basic operators generate elements. Using the split lines, the original boundaries are split recursively until each loop contains a certain number of key nodes, and then using the basic operators such as type-1 and type-2, one or two triangular elements are generated at each operation. After the triangulation process has been completed for each meshing domain, the resulting meshes are finally improved by smoothing process. Sample meshes are presented to demonstrate the versatility of the algorithm.

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A Study on the 3D Object Representation based WebSD Using X3D (X3D를 이용한 WebSD기반 3D Object 표현에 대한 연구)

  • 이성태;김이선;기우용;이윤배
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.4
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    • pp.632-638
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    • 2002
  • Extensible 3D(X3D) is a software standard for defining interactive web and broadcast-based 3D content integrated with multimedia. The data size of Web3D representation based on polygon meshes is so large that transferring practical data fast is a hard problem. This paper proposes 3D object structure, a new framework for compact 3D representation with high quality surface shape. By utilizing a free form surface technique, qualified surface are transferred with limited amount of data size and rendered. 3D graphic structure can be regarded ad both polygon meshes and free form surfaces. Therefore, it can be easily integrated to existing Web3D data formats, for example VRML & XML. 3D object structure also enables modeling free form surface shapes intuitively with polygon modeling like operations.

User-Steered Extraction of Geometric Features for 3D Triangular Meshes (사용자 의도에 의한 삼차원 삼각형 메쉬의 기하적 특징 추출)

  • Yoo, Kwan-Hee;Ha, Jong Sung
    • Journal of the Korea Computer Graphics Society
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    • v.9 no.2
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    • pp.11-18
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    • 2003
  • For extracting geometric features in 3D meshes according to user-steering with effective interactions. this paper generalizes the 2D algorithms of snapping and wrapping that. respectively. moves a cursor to a nearby feature and constructs feature boundaries. First. we define approximate curvatures and move cost functions that are the numerical values measuring the geometric characteristics of the meshes, By exploiting the measuring values. the algorithms of geometric snapping and geometric wrapping are developed and implemented. We also visualize the results from applying the algorithms to extracting geometric features of general 3D mesh models such as a face model and a tooth model.

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3D Mesh Simplification Using Subdivided Edge Classification (세분화된 에지 분류 방법을 이용한 삼차원 메쉬 단순화)

  • 장은영;호요성
    • Proceedings of the IEEK Conference
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    • 2000.11c
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    • pp.109-112
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    • 2000
  • Many applications in computer graphics require highly detailed complex models. However, the level of detail may vary considerably according to applications. It is often desirable to use approximations in place of excessively detailed models. We have developed a surface simplification algorithm which uses iterative contractions of edges to simplify models and maintains surface error approximations using a quadric metric. In this paper, we present an improved quadric error metric for simplifying meshes. The new metric, based on subdivided edge classification, results in more accurate simplified meshes. We show that a subdivided edge classification captures discontinuities efficiently. The new scheme is demonstrated on a variety of meshes.

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Generation of Fixed Spectral Basis for Three-Dimensional Mesh Coding Using Dual Graph

  • Kim Sung-Yeol;Yoon Seung-Uk;Ho Yo-Sung
    • Proceedings of the IEEK Conference
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    • summer
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    • pp.137-142
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    • 2004
  • In this paper, we propose a new scheme for geometry coding of three-dimensional (3-D) mesh models using a fixed spectral basis. In order to code the mesh geometry information, we generate a fixed spectral basis using the dual graph derived from the 3-D mesh topology. After we partition a 3-D mesh model into several independent sub-meshes to reduce coding complexity, the mesh geometry information is projected onto the generated orthonormal bases which are the eigenvectors of the Laplacian matrix of the 3-D mesh. Finally, spectral coefficients are coded by a quantizer and a variable length coder. The proposed scheme can not only overcome difficulty of generating a fixed spectral basis, but also reduce coding complexity. Moreover, we can provide an efficient multi-resolution representation of 3-D meshes.

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