• Title, Summary, Keyword: Shape Model

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Organ Shape Modeling Based on the Laplacian Deformation Framework for Surface-Based Morphometry Studies

  • Kim, Jae-Il;Park, Jin-Ah
    • Journal of Computing Science and Engineering
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    • v.6 no.3
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    • pp.219-226
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    • 2012
  • Recently, shape analysis of human organs has achieved much attention, owing to its potential to localize structural abnormalities. For a group-wise shape analysis, it is important to accurately restore the shape of a target structure in each subject and to build the inter-subject shape correspondences. To accomplish this, we propose a shape modeling method based on the Laplacian deformation framework. We deform a template model of a target structure in the segmented images while restoring subject-specific shape features by using Laplacian surface representation. In order to build the inter-subject shape correspondences, we implemented the progressive weighting scheme for adaptively controlling the rigidity parameter of the deformable model. This weighting scheme helps to preserve the relative distance between each point in the template model as much as possible during model deformation. This area-preserving deformation allows each point of the template model to be located at an anatomically consistent position in the target structure. Another advantage of our method is its application to human organs of non-spherical topology. We present the experiments for evaluating the robustness of shape modeling against large variations in shape and size with the synthetic sets of the second cervical vertebrae (C2), which has a complex shape with holes.

Face Tracking System using Active Appearance Model (Active Appearance Model을 이용한 얼굴 추적 시스템)

  • Cho, Kyoung-Sic;Kim, Yong-Guk
    • 한국HCI학회:학술대회논문집
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    • pp.1044-1049
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    • 2006
  • 얼굴 추적은 Vision base HCI의 핵심인 얼굴인식, 표정인식 그리고 Gesture recognition등의 다른 여러 기술을 지원하는 중요한 기술이다. 이런 얼굴 추적기술에는 영상(Image)의 Color또는 Contour등의 불변하는 특징들을 사용 하거나 템플릿(template)또는 형태(appearance)를 사용하는 방법 등이 있는데 이런 방법들은 조명환경이나 주위 배경등의 외부 환경에 민감하게 반응함으로 해서 다양한 환경에 사용할 수 없을 뿐더러 얼굴영상만을 정확하게 추출하기도 쉽지 않은 실정이다. 이에 본 논문에서는 deformable한 model을 사용하여 model과 유사한 shape과 appearance를 찾아 내는 AAM(Active Appearance Model)을 사용하는 얼굴 추적 시스템을 제안하고자 한다. 제안된 시스템에는 기존의 Combined AAM이 아닌 Independent AAM을 사용하였고 또한 Fitting Algorithm에 Inverse Compositional Image Alignment를 사용하여 Fitting 속도를 향상 시켰다. AAM Model을 만들기 위한 Train set은 150장의 4가지 형태에 얼굴을 담고 있는 Gray-scale 영상을 사용 하였다. Shape Model은 각 영상마다 직접 표기한 47개의 Vertex를 Trianglize함으로서 생성되는 71개의 Triangles을 하나의 Mesh로 구성하여 생성 하였고, Appearance Model은 Shape 안쪽의 모든 픽셀을 사용해서 생성하였다. 시스템의 성능 평가는 Fitting후 Shape 좌표의 정확도를 측정 함으로서 평가 하였다.

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Lip Recognition Using Active Shape Model and Shape-Based Weighted Vector (능동적 형태 모델과 가중치 벡터를 이용한 입술 인식)

  • 장경식
    • Journal of Intelligence and Information Systems
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    • v.8 no.1
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    • pp.75-85
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    • 2002
  • In this paper, we propose an efficient method for recognizing lip. Lip is localized by using the shape of lip and the pixel values around lip contour. The shape of lip is represented by a statistically based active shape model which learns typical lip shape from a training set. Because this model is affected by the initial position, we use a boundary between upper and lower lip as initial position for searching lip. The boundary is localized by using a weighted vector based on lip's shape. The experiments have been performed for many images, and show very encouraging result.

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Lip Shape Representation and Lip Boundary Detection Using Mixture Model of Shape (형태계수의 Mixture Model을 이용한 입술 형태 표현과 입술 경계선 추출)

  • Jang Kyung Shik;Lee Imgeun
    • Journal of Korea Multimedia Society
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    • v.7 no.11
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    • pp.1531-1539
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    • 2004
  • In this paper, we propose an efficient method for locating human lips. Based on Point Distribution Model and Principle Component Analysis, a lip shape model is built. Lip boundary model is represented based on the concatenated gray level distribution model. We calculate the distribution of shape parameters using Gaussian mixture. The problem to locate lip is simplified as the minimization problem of matching object function. The Down Hill Simplex Algorithm is used for the minimization with Gaussian Mixture for setting initial condition and refining estimate of lip shape parameter, which can refrain iteration from converging to local minima. The experiments have been performed for many images, and show very encouraging result.

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A New Shape-Based Object Category Recognition Technique using Affine Category Shape Model (Affine Category Shape Model을 이용한 형태 기반 범주 물체 인식 기법)

  • Kim, Dong-Hwan;Choi, Yu-Kyung;Park, Sung-Kee
    • The Journal of Korea Robotics Society
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    • v.4 no.3
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    • pp.185-191
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    • 2009
  • This paper presents a new shape-based algorithm using affine category shape model for object category recognition and model learning. Affine category shape model is a graph of interconnected nodes whose geometric interactions are modeled using pairwise potentials. In its learning phase, it can efficiently handle large pose variations of objects in training images by estimating 2-D homography transformation between the model and the training images. Since the pairwise potentials are defined on only relative geometric relationship betweenfeatures, the proposed matching algorithm is translation and in-plane rotation invariant and robust to affine transformation. We apply spectral matching algorithm to find feature correspondences, which are then used as initial correspondences for RANSAC algorithm. The 2-D homography transformation and the inlier correspondences which are consistent with this estimate can be efficiently estimated through RANSAC, and new correspondences also can be detected by using the estimated 2-D homography transformation. Experimental results on object category database show that the proposed algorithm is robust to pose variation of objects and provides good recognition performance.

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MULTI-SHAPE ERYTHROCYTE IMAGING AND THEIR DEFORMABILITY ANALYSIS IN A MICROFLUIDIC ENVIRONMENT

  • Jayavanth, Sanjay;Pak, Bock-Choon
    • Proceedings of the KSME Conference
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    • pp.2791-2796
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    • 2007
  • In their long journey through the cardiovascular circuit, erythrocytes are coerced to shape transform and assume different shapes on account of varying flow conditions in different blood vessels. The present work was aimed to visualize these erythrocyte shape transformations by an invitro microcirculatory model, and assess multi-shape erythrocyte deformability. The model uses an in-house fabricated, inexpensive disposable micro flow channel to mimic certain invivo conditions and a fast frame video microscopic system for imaging the shape changes in erythrocytes. Results show the multi-shape transformation of erythrocyte christened as discoidal shape, the asymmetrically deformed 'hat' and 'bullet-like' shapes, and the axially deformed 'slipper' and 'spindle-like' shapes. Specific erythrocyte showed the shape transition and transformation while passing through the observed window. The obtained erythrocyte shapes very analyzed for deformability index using image processing techniques that varied significantly (p <0.001) for different shapes as compared with the resting shape.

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Lip Recognition using Lip Shape Model and Down Hill Search Method (입술의 형태 모델과 Down Hill 탐색 방법을 이용한 입술 인식)

  • 이임건;장경식
    • Journal of Korea Multimedia Society
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    • v.6 no.6
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    • pp.968-976
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    • 2003
  • In this paper, we propose a novel method for lip recognition. Lip model is built based on the concatenated gray level distribution model, and the recognition problem is simplified as the minimization problem of matching object function. The Down Hill Simplex Algorithm is used for the minimization with the proposed novel method for setting initial condition, which can refrain Iteration from converging to local minima. The proposed algorithm shows extracting lip shape from the test image where Active Shape Model fails.

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Modeling of chloride diffusion in concrete considering wedge-shaped single crack and steady-state condition

  • Yang, Keun-Hyeok;Cheon, Ju Hyun;Kwon, Seung-Jun
    • Computers and Concrete
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    • v.19 no.2
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    • pp.211-216
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    • 2017
  • Crack on concrete surface allows more rapid penetration of chlorides. Crack width and depth are dominant parameters for chloride behavior, however their effects on chloride penetration are difficult to quantify. In the present work, the previous anisotropic (1-D) model on chloride diffusion in concrete with single crack is improved considering crack shape and roughness. In the previous model, parallel-piped shape was adopted for crack shape in steady-state condition. The previous model with single crack is improved considering wedge shape of crack profile and roughness. For verifying the proposed model, concrete samples for nuclear power plant are prepared and various crack widths are induced 0.0 to 1.2 mm. The chloride diffusion coefficients in steady-state condition are evaluated and compared with simulation results. The proposed model which can handle crack shape and roughness factor is evaluated to decrease chloride diffusion and can provide more reasonable results due to reduced area of crack profile. The roughness effect on diffusion is evaluated to be 10-20% of reduction in chloride diffusion.

Optimum Shape Design of Engine Mounting Rubber Using a Parametric Approach (형상 파라미터화 방법을 이용한 엔진 마운트용 고무의 형상 최적화)

  • Kim, J.J.;Kim, H.Y.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.2
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    • pp.33-41
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    • 1994
  • The procedure to design the engine mount is briefly discussed and the optimum shape design process of engine mounting rubber using a parametric approach is suggested. An optimization code is developed to determine the shape to meet the stiffness requirements of engine mounts, coupled with the commercial nonlinear finite element program ABAQUS. A bush type engine mount used in a current passenger car is chosen for an application model. The shape from the result of the parameter optimization is determined as a final model with some modifications. The shape and stiffness of each optimization stage are shown and the stiffness of the optimized model along the principal direction is compared with the design specification of the current model. Finally, an overview of the current status and future works for the engine mount design are discussed.

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