• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권1호
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• pp.228-246
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• 2011

A 3D model based approach for a face representation and recognition algorithm has been investigated as a robust solution for pose and illumination variation. Since a generative 3D face model consists of a large number of vertices, a 3D model based face recognition system is generally inefficient in computation time and complexity. In this paper, we propose a novel 3D face representation algorithm based on a pixel to vertex map (PVM) to optimize the number of vertices. We explore shape and texture coefficient vectors of the 3D model by fitting it to an input face using inverse compositional image alignment (ICIA) to evaluate face recognition performance. Experimental results show that the proposed face representation and recognition algorithm is efficient in computation time while maintaining reasonable accuracy.

• 정보처리학회논문지B
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• 제16B권1호
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• pp.47-54
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• 2009

측정점으로부터의 3차원 객체 자동인식은 컴퓨터비전, 지능형로봇 등의 분야에서 주요 연구주제이다. 본 논문에서 저자는 측정오차가 포함되어 있으며 정렬되지 않은 대용량 3차원 측정점으로부터 객체를 자동적으로 추출하며 그 형상계수를 추정하는 소프트웨어 기술에 대한 소개를 하고자 한다. 해당 소프트웨어는 기능적으로 상호 연결된 형상모델 제시, 측정점 분할, 형상모델 맞춤의 세 부분으로 이루어졌으며 최단거리 최소제곱법(ODF)이 핵심요소이다. ODF는 형상모델과 측정점 사이의 최단거리의 제곱합을 최소화하는 형상모델 계수를 추정한다. 무작위로 선정된 부분 측정점에 대한 임시 형상모델로서 이차 곡면이 ODF에 의하여 구하여지면 우리는 이로부터 3차원 객체를 자동적으로 추출하는 과정인 최종 형상모델 제시, 측정점 분할, 형상모델 맞춤에 필요한 초기값을 제공할 수 있다. 소개된 소프트웨어 기술을 실제 3차원 측정점에 적용함으로써 그의 성능을 확인하고자 한다.

• 전자공학회논문지
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• 제52권4호
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• pp.135-144
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• 2015

지문의 땀샘(pore)은 지문인식 분야에서 아주 유용한 특징의 하나이고 땀샘에 기반한 지문인식 시스템도 많이 제안되었다. 땀샘 정보를 이용하여 지문을 인식하려면 땀샘을 정확하게 추출하는 것이 아주 중요하다. 기존의 땀샘 추출 방법은 2차원 모델정합 기법을 이용하여 땀샘 중심을 검출한다. 본 논문에서는 2차원 모델보다 간단한 1차원 가우시안 모델을 이용한 땀샘 추출 방법을 제안한다. 1차원 모델을 이용하여 모델정합하는 과정에 2차원 모델보다 적은 연산량을 필요한다는 장점이 있다. 제안하는 방법은 먼저 국부적 융선(ridge)의 방향을 계산하고 융선 마스크(ridge mask)를 생성한 다음 땀샘 중심이 주변보다 밝다는 성질을 이용하여 사이즈가 각각 $3{\times}3$과 $5{\times}5$인 필터로 땀샘 후보를 찾는다. 검출된 땀샘 후보에 대하여 1차원 가우시간 모델정합을 적용하여 땀샘 중심을 검출한다. 땀샘 추출 실험을 통하여 제안하는 방법은 기존의 2차원 모델에 기반한 방법보다 더 높은 땀샘 검출률을 보여주었고 땀샘 매칭 실험을 통하여 제안하는 땀샘 추출 방법이 지문인식에 사용될 수 있음을 보여준다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2021년도 추계학술대회
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• pp.212-214
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• 2021

In a society with Covid-19 as part of our daily lives, we had to adapt ourselves to a new reality to maintain our lifestyles as normal as possible. An example of this is teleworking and online classes. However, several issues appeared on the go as we started the new way of living. One of them is the doubt of knowing if real people are in front of the camera or if someone is paying attention during a lecture. Therefore, we encountered this issue by creating a 3D reconstruction tool to identify human faces and expressions actively. We use a web camera, a lightweight 3D face model, and use the 2D facial landmark to fit expression coefficients to drive the 3D model. With this Model, it is possible to represent our faces with an Avatar and fully control its bones with rotation and translation parameters. Therefore, in order to reconstruct facial expressions during online meetings, we proposed the above methods as our solution to solve the main issue.

• 제어로봇시스템학회논문지
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• 제17권8호
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• pp.768-776
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• 2011

This paper considers a data fitting problem for rational function models using the LM (Levenberg-Marquardt) optimization method. Rational function models have various merits on representing a wide range of shapes and modeling complicated structures by polynomials of low degrees in both the numerator and denominator. However, rational functions are nonlinear in the parameter vector, thereby requiring nonlinear optimization methods to solve the fitting problem. In this paper, we propose a data fitting method for rational function models based on the LM algorithm which is renowned as an effective nonlinear optimization technique. Simulations show that the fitting results are robust against the measurement noises and uncertainties. The effectiveness of the proposed method is further demonstrated by the real application to a 3D depth camera calibration problem.

• 패션비즈니스
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• 제8권4호
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• pp.94-103
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• 2004

The purpose of this study was to make activated electronic business transaction of clothes. The subject used for this study was 19 - 24 aged 149 college women who most likely buying products through internet. By compare the 149 women's body shape with 3D model, 149 women could be judged their body shape objectively. We showed the average 3D model by the measurement of 19 - 24aged women's body shape. 19 - 24aged women are big customer of internet shopping mall. By understanding of the difference between real somatotype and perceptual somatotype, we can reduce the disadvantage such as returning clothes. Also, imaginary fitting model can be used for internet shopping mall, animation work, fashion show, and advertisement work. Therefore, we can expect the worth of this study to do.

• 대한전자공학회논문지SP
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• 제41권4호
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• pp.51-61
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• 2004

치과 분야에서 치아가 개별적으로 조작될 수 있는 3차원 치아 모델은 치과 치료와 시술 시뮬레이션을 위해 중요한 요소이다. CT영상으로부터 이러한 치아 모델을 재구성하기 위해서는 각 치아의 경계를 정확하게 분할할 수 있어야 한다. 그러나 기존의 3차원 재구성 시스템에서 사용되는 임계화 방법은 치아들과 치아와 비슷한 밝기의 치조골이 서로 인접해서 나타나는 CT 영상열에서 효율적이지 못하다. 본 논문에서는 CT영상에서 부드러운 치아 경계를 추출하기 위해 B-spline 곡선 적합을 이용한 치아 분할 방법을 제안한다. 성공적인 적합을 위해서 이전 슬라이스의 분할정보와 적응 최적 임계화 방법을 기반으로 한 초기경계 생성방법을 제안한다. 그리고 적합과정에서 이웃한 유사한 물체에 적합되는 것을 줄일 수 있는 유전자 알고리즘을 이용한 B-spline 적합방법을 제안한다. 평가결과 제안된 알고리즘은 개별치아의 경계를 성공적으로 검출하였으며 이를 이용하여 시술과 치료 과정의 시뮬레이션을 위한 치아의 3차원 모델을 정확하고 부드럽게 생성할 수 있음을 보였다.

• Journal of Mechanical Science and Technology
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• 제20권12호
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• pp.2034-2042
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• 2006

In this study, a complete 3D surface reconstruction method is proposed based on the concept that the vertices, of surface model can be completely matched to the unstructured point cloud. In order to generate the initial mesh model from the point cloud, the mesh subdivision of bounding box and shrink-wrapping algorithm are introduced. The control mesh model for well representing the topology of point cloud is derived from the initial mesh model by using the mesh simplification technique based on the original QEM algorithm, and the parametric surface model for approximately representing the geometry of point cloud is derived by applying the local subdivision surface fitting scheme on the control mesh model. And, to reconstruct the complete matching surface model, the insertion of isolated points on the parametric surface model and the mesh optimization are carried out. Especially, the fast 3D surface reconstruction is realized by introducing the voxel-based nearest-point search algorithm, and the simulation results reveal the availability of the proposed surface reconstruction method.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.161-162
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• 1997

It is very useful to perform the surgery simulation before implanting TAH(Total Artificial Heart} in a patient. The space of chest and the shape of vessels are different from patient to patient. So, It is desirable to customize a TAH design to the anatomy structure of a patient. Several studies are performed to visualize and explain the 3D structure of heart. These studies are performed using 2-dimensional ref or mated images and simple measurement. Anatomy structure of a human heart is not so simple. It is 4dimensional structure ; 3-dimensional plus time, heart beating. 3-dimensional reconstruction schemes of medical images developed for about 10 years are usually categorized into two types of rendering technique ; surface rendering and volume rendering. Volume rendering is preferable in medical image processing field because this technique can be applied without considering the complexity of geometry and change of field of interest. The usable space in the chest of patient can be measured by 3D volume matching of patient trunk and TAH model. This space changes with time. In this research we have developed the 4-dimensional volume match program of patient and TAH model. 3-dimensional rendered set of volumes along time were used to simulate TAH fitting trial. The quantitative measurement from this simulation could be applied to customize TAH design.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2782-2805
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• 2018

We present a legorization framework that produces a LEGO model from user-specified 3D mesh model. Our framework is composed of two stages: voxelization and legorization. In the voxelization, input 3D mesh is converted to a voxel model. To preserve the shape of the 3D mesh, we devise a silhouette fitting process for the initial voxel model. For legorization, we propose three objectives: stability, aesthetics and efficiency. These objectives are expressed in a tiling equation, which builds a LEGO model using layer-by-layer approach. We legorize five models including characters and buildings to prove the excellence of our framework.