• 제목/요약/키워드: triangular mesh

검색결과 190건 처리시간 0.028초

등고선 데이터를 이용한 산악지형 유동해석 격자생성 프로그램 개발 및 그 응용 (The development of a mesh generation program using contour line data)

  • 진상문;원찬식;허남건
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2004년도 춘계 학술대회논문집
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    • pp.202-207
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    • 2004
  • In the present study a mesh generation program has been developed by using DXF file. The program consists of DXF file reading and mapping algorithm, which projects the 2-D mesh point onto the triangular surface constructed by nearest three points. The present program has been tested for mesh generations for the road tunnel ventilation analysis and analysis of lava movement in mountain area.

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삼각분할된 3차원 실내공간데이터를 OGC IndoorGML로 변환하는 방법 (Converting Triangulated 3D Indoor Mesh Data to OGC IndooGML)

  • 이기준;김동민
    • 한국측량학회지
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    • 제36권6호
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    • pp.499-505
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    • 2018
  • 지금까지 만들어지고 있는 실내공간데이터는 공간적 활용을 위한 데이터라고 하기 보다는 삼각분할로 표현된 3DS나 COLLADA 형식의 가시화 데이터이다. 의미 있는 공간분석이나 실내응용서비스를 개발하기 위하여서는 단순히 삼각분할로 만들어진 가시화데이터가 아니라 의미적 공간정보가 필요하다. OGC (Open Geospatial Consortium) 표준인 IndoorGML(Indoor Geographic Markup Language)은 가시화가 아니라 실내공간 분석을 비롯한 다양한 응용을 위하여 만들어진 공간데이터 형식이다. 따라서 삼각분할로 표현된 3DS나 COLLADA형식의 실내 공간데이터를 OGC IndoorGML 형식으로 변환하는 것은 중요한 작업이 된다. 본 논문에서는 이 문제를 해결하기 위하여, 삼각분할 형식으로 표현된 원시 실내 공간데이터를 기하, 위상, 그리고 의미적으로 유용한 IndoorGML로 변환하는 방법을 제시한다. 또한 이 변환 방법의 타당성을 위하여 개발된 도구도 함께 소개한다. 실제 데이터를 통한 실험을 통하여 이 방법과 개발된 도구를 검증하였다.

Machining Tool Path Generation for Point Set

  • Park, Se-Youn;Shin, Ha-Yong
    • International Journal of CAD/CAM
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    • 제8권1호
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    • pp.45-53
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    • 2009
  • As the point sampling technology evolves rapidly, there has been increasing need in generating tool path from dense point set without creating intermediate models such as triangular meshes or surfaces. In this paper, we present a new tool path generation method from point set using Euclidean distance fields based on Algebraic Point Set Surfaces (APSS). Once an Euclidean distance field from the target shape is obtained, it is fairly easy to generate tool paths. In order to compute the distance from a point in the 3D space to the point set, we locally fit an algebraic sphere using moving least square method (MLS) for accurate and simple calculation. This process is repeated until it converges. The main advantages of our approach are : (1) tool paths are computed directly from point set without making triangular mesh or surfaces and their offsets, and (2) we do not have to worry about no local interference at concave region compared to the other methods using triangular mesh or surface model. Experimental results show that our approach can generate accurate enough tool paths from a point set in a robust manner and efficiently.

셸 구조물의 중간면에 대한 삼각형 셸 요소망의 자동생성 (Automatic Generation of Triangular Shell Element Meshes on Mid-Surface in Shell Structure)

  • 문연철;양현익
    • 대한기계학회논문집A
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    • 제31권4호
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    • pp.451-460
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    • 2007
  • The surface of 3D shell structure is created by using NURBS and nodes for generating finite element mesh on the surface are created by using external node offset method. In so doing the shortest distance between nodes on the top and bottom surface is searched and then the coordinates of nodes are determined by calculating the mid point of them in the middle of top and bottom surface. Triangular elements are formed on mid surface, and the average aspect ratio of the generated triangular elements are over 0.9.

랜덤 패턴 투영을 이용한 스테레오 비전 시스템 기반 3차원 기하모델 생성 (3D geometric model generation based on a stereo vision system using random pattern projection)

  • 나상욱;손정수;박형준
    • 한국경영과학회:학술대회논문집
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    • 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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    • pp.848-853
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    • 2005
  • 3D geometric modeling of an object of interest has been intensively investigated in many fields including CAD/CAM and computer graphics. Traditionally, CAD and geometric modeling tools are widely used to create geometric models that have nearly the same shape of 3D real objects or satisfy designers intent. Recently, with the help of the reverse engineering (RE) technology, we can easily acquire 3D point data from the objects and create 3D geometric models that perfectly fit the scanned data more easily and fast. In this paper, we present 3D geometric model generation based on a stereo vision system (SVS) using random pattern projection. A triangular mesh is considered as the resulting geometric model. In order to obtain reasonable results with the SVS-based geometric model generation, we deal with many steps including camera calibration, stereo matching, scanning from multiple views, noise handling, registration, and triangular mesh generation. To acquire reliable stere matching, we project random patterns onto the object. With experiments using various random patterns, we propose several tips helpful for the quality of the results. Some examples are given to show their usefulness.

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비정렬 격자계에서 격자계 구성방법에 따른 계산의 정확도와 효율에 관한 연구 (On the Accuracy and Efficiency of Calculation with Respect to the Grid Construction Methods for Unstructured Meshes)

  • 김사량
    • 한국전산유체공학회지
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    • 제9권1호
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    • pp.48-56
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    • 2004
  • The numerical simulations with unstructured mesh by cell-centered and vertex-centered approaches were peformed for the quadrilateral and triangular meshes. For 2-D inviscid supersonic vortex flow, the simulation results and the analytic solution were compared and the accuracy was assessed. The calculation efficiency was measured by the parameter defined by the consumed CPU time multiplied by absolute error As a results, equilateral triangular mesh yielded the best accuracy and efficiency among the tested meshes. Cell-centered approach gives a little better efficiency than vertex - centered approach.

솔리드 STL 모델의 옵셋 방법 (Offset of STL Model Generated from Solid Model)

  • 김수진;양민양
    • 한국정밀공학회지
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    • 제22권9호
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    • pp.202-211
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    • 2005
  • This paper introduces and illustrates the results of a new method fer offsetting triangular mesh by moving all vertices along the multiple normal vectors of a vertex. The multiple normal vectors of a vertex are set the same as the normal vectors of the faces surrounding the vertex, while the two vectors with the smallest difference are joined repeatedly until the difference is smaller than allowance. Offsetting with the multiple normal vectors of a vertex does not create a gap or overlap at the smooth edges, thereby making the mesh size uniform and the computation time short. In addition, this offsetting method is accurate at the sharp edges because the vertices are moved to the normal directions of faces and joined by the blend surface. The method is also useful for rapid prototyping and tool path generation if the triangular mesh is tessellated part of the solid models with curved surfaces and sharp edges. The suggested method and previous methods are implemented on a PC using C++ and illustrated using an OpenGL library.

비조직화된 점군으로부터 NURBS 곡면 모델의 생성 (NURBS Surface Reconstruction from an Unstructured Point Cloud)

  • 이일섭;김석일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회A
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    • pp.1564-1569
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    • 2007
  • This study concerns an advanced NURBS surface reconstruction method, which is based on the NURBS surface model fitting to the unstructured point cloud measured from an arbitrary complex shape. The concept of generating a simple triangular mesh model was introduced to generate a quadrilateral mesh model well-representing the topological characteristics of point cloud. The NURBS surface reconstruction processes required the use of the various methodologies such as QEM algorithm, merging scheme of pair-wise triangular mesh, creation algorithm of $G^1$ continuous tensor product NURBS surface patch, and so on. The effectiveness and reliability of the proposed NURBS surface reconstruction method were validated through the simulation results for the geometrically and topologically complex shapes.

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절점과 요소의 동시 생성을 위한 삼각 요소 알고리즘 (Triangular Mesh Generation Algorithm for Generating Nodes and Triangular Elements Concurrently)

  • 천재홍;양현익
    • 한국CDE학회논문집
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    • 제5권3호
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    • pp.207-214
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    • 2000
  • For last 20 years, a number of researches and developments on finite element mesh generation has been carried out and most of them are comported of node generation part and node generation part. However these algorithms are inefficient in mesh veneration process and difficult to control the shape of elements when comparing with the generation of nodes and elements concurrently. In this study, therefore, an algorithm it proposed to generate nodes and elements concurrently for various two-dimensional objects having multiple holes. Inner node generation is performed by choosing three consecutive boundary nodes and comparing them with other close boundary nodes. As soon as inner nodes are determined, element generation is conducted based on the comparison of the distances among the generated inner nodes, three consecutive boundary nodes and other close boundary nodes. the generated element nodes become new boundary nodes for further repeated process. The processes are repeated through out each region until three consecutive boundary nodes finally form a tirangular element.

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3차원 적응 유한요소법을 위한 사면체 요소세분에 관한 연구 (A Study on Mesh Refinement for 3-D Adaptive Finite Element Method Using Tetrahedral Element)

  • 김형석;정현교;한송엽
    • 대한전기학회논문지
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    • 제39권9호
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    • pp.921-927
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    • 1990
  • This paper presents a mesh refinement scheme for 3-D adaptive finite element method. Firstly, the refinement of triangular meshes based on the bisection of triangles is discussed. And a new method to refine tetrahedral meshes employing the bisection method is presented. In two dimensional cases, it has been noted that all angles in the triangular meshes refined by the bisection method are greater than or equal to half the smallest angle in the original meshes. Through the examples where the newly proposed method is applied to three dimensional cases, it is shown that regarding the solid angles, the method gives nearly the same result as that in the two dimensional case. Accordingly, it can be concluded that the proposed method will be useful in the mesh refinements for 3-D adaptive finite element method.

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