• Title/Summary/Keyword: 정점선택

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A Two-Step Vertex Selection Method for Minimizing Polygonal Approximation Error (다각형 근사 오차를 최소화하기 위한 2단계 정점 선택 기법)

  • 윤병주;이훈철;고윤호;이시웅;김성대
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.40 no.6
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    • pp.114-123
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    • 2003
  • The current paper proposes a new vertex selection scheme for polygon-based contour coding. To efficiently characterize the shape of an object, we incorporate the curvature information in addition to the conventional maximum distance criterion in vertex selection process. The proposed method consists of "two-step procedure." At first, contour pixels of high curvature value are selected as key vortices based on the curvature scale space (CSS), thereby dividing an overall contour into several contour-segments. Each segment is considered as an open contour whose end points are two consecutive key vortices and is processed independently. In the second step, vertices for each contour segment are selected using progressive vertex selection (PVS) method in order to obtain minimum number of vertices under the given maximum distance criterion ( $D_{max}$$^{*}$). Furthermore, the obtained vortices are adjusted using the dynamic programming (DP) technique to optimal positions in the error area sense. Experimental results are presented to compare the approximation performances of the proposed and conventional methods.imation performances of the proposed and conventional methods.

An Efficient Polygonal Approximation Method in the Rate-Distorion Sense (비트량-왜곡을 고려한 효율적인 다각형 근사화 기법)

  • 윤병주;고윤호;김성대
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.40 no.1
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    • pp.114-123
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    • 2003
  • This paper proposes an efficient method for encoding the shape information of the object in the image. The polygonal approximation method is categorized into a loss coding method and is widely used for approximating object's shape information. The proposed method selects less number of vertices than IRM (iterated refinement method) or PVS (progressive vertex selection) when the maximum distortion is given, so reduces the bit-rates. The proposed method selects the vertices of a polygon with a simple and efficient method considering the rate-distortion sense. We construct the shape information coder, which shows the outstanding performance in the rate-distortion sense, based on the conventional progressive vertex selection method and the new vertex selection condition that we propose in this paper. Simulation results show that the proposed method has better performance than other conventional vertex selection methods in the tate-distortion sense.

Inter-frame vertex selection algorithm for lossy coding of shapes in video sequences (동영상에서의 모양 정보 부호화를 위한 정점 선택 알고리즘)

  • Suh, Jong-Yeul;Kim, Kyong-Joong;Kang, Moon-Gi
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.37 no.4
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    • pp.35-45
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    • 2000
  • The vertex-based boundary encoding scheme is widely used in object-based video coding area and computer graphics due to its scalability with natural looking approximation. Existing single framebased vertex encoding algorithm is not efficient for temporally correlated video sequences because it does not remove temporal redundancy. In the proposed method, a vertex point is selected from not only the boundary points of the current frame but also the vertex points of the previous frame to remove temporal redundancy of shape information in video sequences. The problem of selecting optimal vertex points is modeled as finding shortest path in the directed acyclic graph with weight The boundary is approximated by a polygon which can be encoded with the smallest number of bits for maximum distortion. The temporal redundancy between two successive frames is efficiently removed with the proposed scheme, resulting in lower bit-rate than the conventional algorithms.

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Heuristic Method for Computing Progressive Mesh Representation between Two Polygonal Models (두 다면체 모델 사이의 점진적 표현을 계산하는 휴리스틱 방법)

  • Yoon, Won-Young;Choi, Jung-Ju;Lee, In-Kwon
    • Journal of the Korea Computer Graphics Society
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    • v.9 no.4
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    • pp.25-30
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    • 2003
  • 본 논문에서는 서로 다른 개수의 정점을 가지는 두 다면체 사이의 점진적 다면체 모델 표현(Progressive Mesh Representation)을 계산하는 휴리스틱 방법을 제시한다. 정점의 개수가 각각 n, k개 인 두 다면체 모델 $M^n$, $M^k$ (n > k)에 대하여 $M^n$에서 서로 다른 k개의 정점을 선택한다. 선택된 k개의 정점을 기준으로 $M^n$의 모든 정점에 대한 클러스터링을 수행하여 k개의 정점군(Vertex Set)을 생성한다. $M^n$을 간략화하여 k개의 정점만을 가지는 모델 $M^{k'}$의 위상정보(Topology)를 $M^k$와 동일하게 유지하기 위하여 $M^n$ 정점군들의 위상정보를 수정한다. 수정 생성된 정점군 내에서 선분병합(Edge Collapse)을 수행하면, 위상정보를 유지하면서 $M^n$에서 $M^k$로 변화하는 점진적 다면체 모델 표현을 얻을 수 있다. $M^{k'}$$M^k$의 정점간의 기하학적 위치차이를 선형보간하여 선분병합이 일어날때 마다 반영하면 $M^n$에서 $M^k$로 기하정보를 부드럽게 유지하면서 변화하는 점진적 다면체 모델 표현을 얻을 수 있다. 본 논문의 연구결과는 기존의 DLoD(Discrete Level of Detail)를 지원하는 게임을 CLoD(Continuous Level of Detail)를 지원하는 게임으로 확장하는 등의 다양한 컴퓨터 그래픽스 응용문제에 사용할 수 있다.

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Hough Transform-based Semi-automatic Vertex Detection Algorithm on a Touch Screen Mobile Phone (모바일 폰 터치스크린에서 허프변환 기반의 반자동식 정점 검출 알고리즘)

  • Jang, Young-Kyoon;Woo, Woon-Tack
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.5
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    • pp.596-600
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    • 2010
  • This paper proposes hough transform-based semi-automatic vertex detection algorithm for object modeling on a mobile phone supporting touch-screens. The proposed algorithm shows fast processing time by searching the limited range of parameters for computing hough transform with a small range of ROI image. Moreover, the proposed algorithm removes bad candidates among the detected lines by selecting the two closest candidate lines from the position of user's input. After that, it accurately detects an interesting vertex without additionally required interactions by detecting an intersection point of the two lines. As a result, we believe that the proposed algorithm shows a 1.4 pixel distance error on average as a vertex detection accuracy under such conditions as a 5.7 pixel distance error on average as an inaccurate input.

Truely Selective Refinement of Progressive Meshes (점진적 메쉬의 엄밀한 선택 세분화 기법)

  • Kim, Jun-Ho;Lee, Seung-Yong
    • Journal of the Korea Computer Graphics Society
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    • v.6 no.3
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    • pp.25-34
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    • 2000
  • 본 논문에서는 점진적 메쉬의 보다 엄밀한 의미에서의 선택적 세분화 방법을 제안한다. 기존의 선택적 세분화 방법은 정점분할 및 에지붕괴 연산이 수행되기 위해서는 현재의 1-고리 이웃 상황이 점진적 메쉬 분석 단계에 기억해 놓은 1-고리 이웃과 같을 때만 올바로 동작하도록 되어 있는 증가적 방법이다. 이러한 증가적 방법은 메쉬의 부분적 해상도 변경을 하게 되면 인접한 부분의 해상도가 그 부분의 해상도를 좇아가게 되는 단점을 가지고 있다. 본 논문에서 제안하는 방법은 점진적 메쉬 표현이 가지는 정점의 계층적 구획화 성질에 기반한 것으로, 원하는 메쉬의 부분에 대해 해상도를 변경할 때, 인접 부분의 정점분할 및 에지붕괴 연산을 초래하지 않아 보다 엄밀한 의미에서의 점진적 메쉬의 선택적 세분화를 수행할 수 있다.

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A New Approach to Selective Refinement of Progressive Meshes (점진적 메쉬의 선택적 세분화를 위한 새로운 접근법)

  • 김준호;이승용
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.04b
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    • pp.652-654
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    • 2000
  • 점진적 메쉐 표현법은 2-다양체 성질을 가지는 임의의 삼각메쉬에 대한 다중해상표현이 가능한 방법으로, 최근 다중해상 모델링 및 렌더링 분야로 그 응용범위를 넓혀가고 있다. 본 논문에서는 점진적 메쉬의 선택적 세분화를 위한 새로운 방법을 제안한다. 제안하는 방법은 기존방법[4,3]과는 달리 거의 대부분의 경우 한 정점의 세분화로 인해 주위 정점이 세분화되지 않는 최적화된 방법이다. 본 논문에서 제안하는 새로운 선택적 세분화방법으로 인해 점진적 메쉬의 활용분야가 더욱 넓어질 것으로 기대된다.

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Efficient Vertex-based Shape Coding using One-dimensional Vertex and Vertex Reordering (1차원 정점과 정점 재배열 이용한 효율적 정점기반 모양정보 부호화)

  • 정재원;문주희;김재균
    • Journal of Broadcast Engineering
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    • v.2 no.2
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    • pp.94-104
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    • 1997
  • This paper presents a new vertex-based binary shape coding scheme using one-dimensional vertex selection/encoding and vertex reordering. In compared with the conventional object-adaptive vertex encoding(OA VEL the extracted vertices are, firstly, classified into one-dimensional(lD) vertices and two-dimensional (2D) vertices in the proposed method. For lD vertices, new coding method proposed in this paper is performed. For 2D vertices, the vertex reordering and OA VE are carried out. Experimental results show that the proposed vertex-based coding scheme red.uces coding bits up to 12 % compared with the conventional one and its coding gain depends on the characteristics of contour.

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The Minimum number of Mobile Guards Algorithm for Art Gallery Problem (화랑 문제의 최소 이동 경비원 수 알고리즘)

  • Lee, Sang-Un;Choi, Myeong-Bok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.3
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    • pp.63-69
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    • 2012
  • Given art gallery P with n vertices, the maximum (sufficient) number of mobile guards is${\lfloor}n/4{\rfloor}$ for simple polygon and${\lfloor}(3n+4)/16{\rfloor}$ for simple orthogonal polygon. However, there is no polynomial time algorithm for minimum number of mobile guards. This paper suggests polynomial time algorithm for the minimum number of mobile guards. Firstly, we obtain the visibility graph which is connected all edges if two vertices can be visible each other. Secondly, we select vertex u with ${\Delta}(G)$ and v with ${\Delta}(G)$ in $N_G(u)$ and delete visible edges from u,v and incident edges. Thirdly, we select $w_i$ in partial graphs and select edges that is the position of mobile guards. This algorithm applies various art galley problems with simple polygons and orthogonal polygons art gallery. As a results, the running time of proposed algorithm is linear time complexity and can be obtain the minimum number of mobile guards.

ECG Signal Compression using Feature Points based on Curvature (곡률을 이용한 특징점 기반 심전도 신호 압축)

  • Kim, Tae-Hun;Kim, Sung-Wan;Ryu, Chun-Ha;Yun, Byoung-Ju;Kim, Jeong-Hong;Choi, Byung-Jae;Park, Kil-Houm
    • Journal of the Korean Institute of Intelligent Systems
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    • v.20 no.5
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    • pp.624-630
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    • 2010
  • As electrocardiogram(ECG) signals are generally sampled with a frequency of over 200Hz, a method to compress diagnostic information without losing data is required to store and transmit them efficiently. In this paper, an ECG signal compression method, which uses feature points based on curvature, is proposed. The feature points of P, Q, R, S, T waves, which are critical components of the ECG signal, have large curvature values compared to other vertexes. Thus, these vertexes are extracted with the proposed method, which uses local extremum of curvatures. Furthermore, in order to minimize reconstruction errors of the ECG signal, extra vertexes are added according to the iterative vertex selection method. Through the experimental results on the ECG signals from MIT-BIH Arrhythmia database, it is concluded that the vertexes selected by the proposed method preserve all feature points of the ECG signals. In addition, they are more efficient than the AZTEC(Amplitude Zone Time Epoch Coding) method.