• Title/Summary/Keyword: 윤곽 오차

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Vertex selection method considering texture degradation for contour approximation (밝기 왜곡을 고려한 윤곽선 근사화용 정점 선택 방법)

  • Choi Jae Gark;Lee Si-Woong;Koh Chang-Rim;Lee Jong-Keuk
    • Journal of Broadcast Engineering
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    • v.10 no.4 s.29
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    • pp.632-642
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    • 2005
  • This paper presents a new vertex selection scheme for the polygon-based contour approximation. In the proposed method, the entire contour is partitioned into partial segments and they are approximated adaptively with variable accuracy. The approximation accuracy of each segment is controlled based on its relative significance. By computing the relative significance with the texture degradation in the approximation error region, the visual quality enhancement in the reconstructed frames can be achieved under the same amount of the contour data. For this purpose, a decision rule for $d_{max}$ is derived based on inter-region contrasts. In addition, an adaptive vertex selection method using the derived rule is proposed. Experimental results are presented to show the superiority of the proposed method over conventional methods.

In-Loop Selective Decontouring Algorithm in Video Coding (비디오 부호화 루프 내에서 의사 윤곽 오차의 선택적 제거 알고리즘)

  • Yoo, Ki-Won;Sohn, Kwang-Hoon
    • Journal of Broadcast Engineering
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    • v.15 no.5
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    • pp.697-702
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    • 2010
  • Contour artifact is known as the unintentional result of quantizing a flat area that has smooth gradients. In this letter, a decontouring algorithm is proposed to efficiently remove false contours that occur in typical block-based video coding applications. First, the algorithm goes through a refinement stage to determine candidate blocks probably having noticeable false contours with different kinds of features in a block. Then, pseudo-random noise masking is applied to those blocks to mitigate the contour artifacts. This block-based selective decontouring can efficiently remove the unnecessary processing of those blocks that have no false contour, which incidentally ensures a minor penalty in visual quality and computational complexity. The proposed algorithm was demonstrated, integrated into H.264/AVC, that visual quality can be significantly enhanced with an ignorable rate-distortion (RD) loss and an minor increase in computational complexity.

Contour Error Analysis and Feed Controller Optimization for Machining Center (머시닝센터를 위한 윤곽오차 분석 및 이송축 제어기 최적화)

  • 김성현;윤강섭;이만형
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.17-24
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    • 2003
  • One of the most important performance criteria related to the gain tuning of controller for CNC machining center is the contour error. This study analyzed circular error by the axis-matched and mismatched cases. To reduce ellipse and radius error, it is necessary to set the gain for each axis to be same bandwidth and high response. Based on the analysis in the frequency domain, we simulate feed system by mathematical model and then predict bandwidth of each axis. For analysis of structure vibration while the each axis is moving, we try the various of measuring method and position loop is improved by jerk limit.

Target Recognition with Intensity-Boundary Features (밝기- 윤곽선 정보 기반의 목표물 인식 기법)

  • 신호철;최해철;이진성;조주현;김성대
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.411-414
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    • 2001
  • 목표물 인식(Target Recognition)에 사용되는 대표적인 특징 정보에는 밝기 (Intensity) 정보와 윤곽선(Boundary) 등의 모양(Shape) 정보가 있다. 그러나, 일반적으로 영상에서 바로 추출한 밝기 정보나 윤곽선 정보는 환경 변화에 의한 많은 오차 요인들을 포함하고 있기 때문에, 이들 특징 정보를 개별적으로 인식에 사용하는 것은 높은 인식 성능을 기대하기 어렵다. 따라서, 밝기 정보와 모양 정보를 인식에 함께 사용하는 기법이 요구된다. 본 논문에서는 밝기 정보와 윤곽선 기반의 모양 정보를 합성하여 동시에 인식에 사용하는 3단계 기법을 제안한다. 제안하는 기법에서 밝기 정보 추출에 는 PCA (Principal Component Analysis)기법을 사용하고 , 윤곽선 정보 추출에는 PDM(Point Distribution Model) 에 기반한 영역 분할(Segmentation) 기법과 Algebraic Curve Fitting기법을 사용하였다 추출된 밝기 정보와 윤곽선 정보는 FLD(Fisher Linear Discriminant) 기법을 통해 결합(integration)되어 인식에 사용 된다. 제안한 기법을 적외선 자동차 영상을 인식하는 실험에 적용한 결과, 기존기법에 비해 인식 성능이 개선됨을 확인할 수 있었다.

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Contouring Error of a Machine Tool at Inflection Points (변곡점에서 공작기계의 윤곽오차)

  • 안일혁;김성수;민경석;최우천;홍대희
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.11
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    • pp.166-170
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    • 2003
  • Contouring errors are important especially for high speed and precision machining. In this study, contouring errors along contours having inflection points are studied. When a table of a machine tool moves along a circular path, acceleration acts toward the center of the circle. Thus, at inflection points, acceleration as well as inertia force changes its direction abruptly. The effect of inertia force on the contouring error is investigated in this study. It is found that the contouring error at an inflection point is proportional to the acceleration. This result can be useful in determining contouring errors along general paths.

Real-Time Pencil Rendering (실시간 연필 렌더링)

  • Lee, Hyun-Jun;Kwon, Sung-Tae;Lee, Seong-Yong
    • Journal of the Korea Computer Graphics Society
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    • v.11 no.4
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    • pp.1-10
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    • 2005
  • 본 논문에서는 주어진 삼차원 메쉬를 실시간에서 연필화로 표현하는 방법을 소개한다. 이를 위해 본 논문에서는 연필화의 특징을 분석한 후 분석된 특징들을 빠르고 간단하게 모사하여 표현하는 알고리즘을 제시한다. 이 알고리즘은 크게 윤곽선을 그리는 방법과 내부를 그리는 방법으로 나뉘며, 제시된 모든 알고리즘은 그래픽스 하드웨어를 이용하여 실시간으로 동작한다. 우선 물체의 윤곽선을 그리기 위해 사람이 윤곽선을 그릴 때의 특징을 분석하여 실제의 윤곽선과 비교해 약간의 오차를 지니면서 여러번 겹쳐 그린 듯한 윤곽선을 만들어 내는 방법을 제시한다. 또한 물체의 내부를 그리기 위해서 먼저 연필의 특징을 잘 반영하는 텍스쳐를 만든 후 이를 물체의 표면에 매핑시켜 물체의 특징을 연필화풍으로 잘 표현하는 방법을 제시한다. 이 과정에서 연필화의 느낌을 강조하기 위해 물체가 그려지는 종이의 질감을 표현하는 방법과 물체의 명암비를 조정하는 방법 역시 제시한다.

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Cross-coupled Control with a New Contour Error Model (새로운 윤곽 오차 모델을 이용한 상호 결합 제어)

  • 이명훈;손희수;양승한
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.341-344
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    • 1997
  • The higher precision in manufacturing field is demanded, the more accurate servo controller is needed. To achieve the high precision, Koren proposed the cross-coupled control (CCC) method. The objective of the CCC is reducing the contour error rather than decreasing the individual axial error. The performance of CCC depends on the contour error model. In this paper we propose a new contour error model which utilizes contour error vector based on parametric curve interpolator. The experimental results show that the new CCC is more accurate than the variable-gain CCC during free-form curve motion.

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Positioning Control through a Trade-off between Tracking Error and Contour Error for a Feed Drive System in CNC Milling Machine (추적오차 및 윤곽오차의 상호 절충을 통한 CNC 밀링머신 이송장치의 위치제어)

  • Gil Hyeong-Gyeun;Yang Ho-Suk;Lee Gun-Bok
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.6
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    • pp.1-7
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    • 2005
  • This paper deals with the position control for a feed drive system in CNC milling machine. The study shows that reduction in tacking error does not necessarily increase contouring accuracy, and proposes that a proper control scheme is able to exhibit the optimal tracking and contouring accuracy. The proposed scheme is to fix the parameter of the contouring control, and to find the optimal value of the parameter of the tracking control, which is automatically tuned. The effectiveness of the proposed scheme is confirmed through simulations.

A New Contour Error Model for Cross-Coupled Controller in CNC Machine Tools (CNC 공작기계에서 상호결합제어기를 위한 새로운 윤곽오차모델)

  • 이재하;양승한
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.152-157
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    • 2000
  • In the control of CNC machine tools, it is significant for precise machining to reduce the contour error. The object of servo-control is reduction of contour error and tracking error. In past studies, there were two approaches to control a servo-system. One was to eliminate axial tracking errors, and the other was to control contour errors. The Cross-coupled controller(CCC) was introduced fro ma veiwpoint of contour error model. Recently, for machining part with free form surfaces, we propose a new contour error model based on curve interpolator. It is presented here that performance of CCC using proposed model is enhanced. Therefore, we can make more precise parts with the curve interpolator and the new contour error model.

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