• Title, Summary, Keyword: octree

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Analysis on Spatial Sampling and Implementation for Primal Trees (Primal Tree의 공간 분할 샘플링 분석 및 구현)

  • Park, Taejung
    • Journal of Digital Contents Society
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    • v.15 no.3
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    • pp.347-355
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    • 2014
  • The general octree structure is common for various applications including computer graphics, geometry information analysis and query. Unfortunately, the general octree approach causes duplicated sample data and discrepancy between sampling and representation positions when applied to sample continuous spatial information, for example, signed distance fields. To address these issues, some researchers introduced the dual octree. In this paper, the weakness of the dual octree approach will be illustrated by focusing on the fact that the dual octree cannot access some specific continuous zones asymptotically. This paper shows that the primal tree presented by Lefebvre and Hoppe can solve all the problems above. Also, this paper presents a three-dimensional primal tree traversal algorithm based the Morton codes which will help to parallelize the primal tree method.

Automatic Generation of 3-D Finite Element Meshes : Part(I) - Tetrahedron-Based Octree Encoding - (삼차원 유한요소의 자동생성 (1) - 사면체 옥트리의 구성 -)

  • 정융호;이건우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3159-3174
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    • 1994
  • A simple octree encoding algorithm based on a tetrahedron root has been developed to be used for fully automatic generation of three dimensional finite element meshes. This algorithm starts octree decomposition from a tetrahedron root node instead of a hexahedron root node so that the terminal mode has the same topology as the final tetrahedral mesh. As a result, the terminal octant can be used as a tetrahedral finite element without transforming its topology. In this part(I) of the thesis, an efficient algorithm for the tetrahedron-based octree is proposed. For this development, the following problems have been solved, : (1) an efficient data structure for storing the octree and finite elements, (2) an encoding scheme of a tetrahedral octree, (3) a neighbor finding technique for the tetrahedron-based octree.

Development of a Cutting Simulation System using Octree Algorithm (옥트리 알고리즘을 이용한 절삭 시뮬레이션 시스템의 개발)

  • Kim Y-H.;Ko S.-L.
    • Korean Journal of Computational Design and Engineering
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    • v.10 no.2
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    • pp.107-113
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    • 2005
  • Octree-based algorithm is developed for machining simulation. Most of commercial machining simulators are based on Z map model, which have several limitations to get a high precision in 5 axis machining simulation. Octree representation is three dimensional decomposition method. So it is expected that these limitations be overcome by using octree based algorithm. By using the octree model, storage requirement is reduced. And also recursive subdivision was processed in the boundaries, which reduces useless computation. The supersampling method is the most common form of the anti-aliasing and usually used with polygon mesh rendering in computer graphics. Supersampling technique is applied for advancing its efficiency of the octree algorithm.

Efficient Octree Encoding for Real-Time Transmission of 3D Geometric Data through Internet (인터넷을 통한 3D 형상 데이터의 실시간 전송을 위한 효율적인 Octree 인코딩 방법에 관한 연구)

  • 류중현;김영우;김덕수
    • Korean Journal of Computational Design and Engineering
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    • v.7 no.4
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    • pp.262-268
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    • 2002
  • Octree representation has the advantage of being able to represent complex shapes approximately through the repetition of simple primitive shapes. Due to this reason, octree representation together with VRML(Virtual Reality Modelling Language) is usually used for approximating 3D shapes. Since the data size of octree representation increases rapidly as 3D shape to be represented is more and more complicated, its transmission time also increase. In this paper, provided is the new octree representation and encoding/decoding scheme for real-time transmission through the internet in order to visualize 3D geometric data of large size approximately.

Octree Generation and Clipping Algorithm using Section Curves for Three Dimensional Cartesian Grid Generation (삼차원 직교 격자 생성을 위한 단면 커브를 이용한 옥트리 생성과 셀 절단 알고리듬)

  • Kim, Dong-Hun;Shin, Ha-Yong;Park, Se-Youn;Yi, Il-Lang;Kwon, Jang-Hyuk;Kwon, Oh-Joon
    • Korean Journal of Computational Design and Engineering
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    • v.13 no.6
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    • pp.450-458
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    • 2008
  • Recently, Cartesian grid approach has been popular to generate grid meshes for complex geometries in CFD (Computational Fluid Dynamics) because it is based on the non-body-fitted technique. This paper presents a method of an octree generation and boundary cell clipping using section curves for fast octree generation and elimination of redundant intersections between boundary cells and triangles from 3D triangular mesh. The proposed octree generation method uses 2D Scan-Converting line algorithm, and the clipping is done by parameterization of vertices from section curves. Experimental results provide octree generation time as well as Cut-cell clipping time of several models. The result shows that the proposed octree generation is fast and has linear relationship between grid generation time and the number of cut-cells.

S-Octree: An Extension to Spherical Coordinates

  • Park, Tae-Jung;Lee, Sung-Ho;Kim, Chang-Hun
    • Journal of Korea Multimedia Society
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    • v.13 no.12
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    • pp.1748-1759
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    • 2010
  • We extend the octree subdivision process from Cartesian coordinates to spherical coordinates to develop more efficient space-partitioning structure for surface models. As an application of the proposed structure, we apply the octree subdivision in spherical coordinates ("S-Octree") to geometry compression in progressive mesh coding. Most previous researches on geometry-driven progressive mesh compression are devoted to improve predictability of geometry information. Unlike this, we focus on the efficient information storage for the space-partitioning structure. By eliminating void space at initial stage and aligning the R axis for the important components in geometry information, the S-Octree improves the efficiency in geometry information coding. Several meshes are tested in the progressive mesh coding based on the S-Octree and the results for performance parameters are presented.

Indexing of 3D Terrain Space for Predicting Collisions with Moving Objects

  • Wu, Wan-Chun;Seo, Young-Duk;Hong, Bong-Hee
    • 한국공간정보시스템학회:학술대회논문집
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    • pp.159-162
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    • 2003
  • In this paper, to find probable collision positions between moving object and terrain in 3D space efficiently, we use a model, similar to Ray Tracing, which finds the triangles intersected by a directed line segment from a large amount of triangles. We try to reduce dead space as much as possible to find candidate triangles intersected by a directed line segment than previous work's. A new modified octree, LBV-Octree(Least Bounding Voxel Octree), is proposed, and we have a ray tracing with it. In the experiment, ray tracing with LBV-Octree provides $5%{\sim}11%$ better performance than with classical octree.

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A Study on Octree Construction Algorithm for 3D Objects (3차원 물체에 대한 8진 트리 구성 알고리즘에 관한 연구)

  • 최윤호;송유진;홍민석;박상희
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.29B no.1
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    • pp.1-10
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    • 1992
  • This study presents a complete octree construction algorithm for 2D depth images obtained from orthogonal face views, which can represent 3D objects exactly. In constructing quadtree, optimal quadtree construction algorithm is applied to depth images for efficient use of memory and reduction of tree construction time. In addition, pseudo-octrees are constructed by using our proposed method, which construct pseudo-octrees according to the resolution value given in each node of constructed quadtree and mapping relation between quadrants and octants. Finally, a complete octree, which represents a 3D object, is constructed by volume intersection with each constructed pseudo-octree. The representation accuracy of a complete octree constructed by our algorithm is investigated by using a 3D display method and a volume ratio method for a complete octree.

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Development of the cutting simulation system with decomposition Algorithm. (분해 모델링 기법을 이용한 절삭 시뮬레이션 시스템 개발)

  • 김용현;고성림
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.422-425
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    • 2004
  • This paper develops an octree-based algorithm for machining simulation. Most commercial machining simulators are based on the Z map model, which has several limitations in terms of achieving a high level of precision in five-axis machining simulation. Octree representation being a three-dimensional (3D) decomposition method, an octree-based algorithm is expected to be able to overcome such limitations. With the octree model, storage requirement is reduced. Moreover, recursive subdivision is processed in the boundaries, which reduces useless computations. The supersampling method is the most common form of antialiasing and is typically used with polygon mesh rendering in computer graphics. The supersampling technique is being used to advance the efficiency of the octree algorithm..

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Three Dimensional Reconstruction and Display of CT Images Via Linear Octree (선형 Octree에 의한 CT영상의 3차원 재구성 및 표현)

  • Yoo, Sun-Kook;Kim, Nam-Hyun;Kim, Won-Ky;Kim, Sun-Ho;Park, Sang-Hui
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.6
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    • pp.79-88
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    • 1989
  • In this paper, linear octree is used to reconstruct and to modify the 3-dimensional image from 2-dimensional cross sections provided by computed tomography. Linear octree introduces a considerable data saving of the memory storage required by small computer system. This structure allows the hidden surface removal utilizing the spatial presortedness of hierarchical octree structure and implementation of graphical operations that include viewing transform and shading. An actual human organ is used to illustrate this technique and its implications for theraphy and surgical planning.

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