• 한국멀티미디어학회논문지
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• 제12권1호
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• pp.50-57
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• 2009

본 논문은 3차원 다각형 모델에서 특징 선을 추출하기 위한 방법에 대해 제안한다. 이산 곡면으로 이루어진 다각형 모델에서 특징 선을 추출하기 위하여 기존 방법에서는 전역적인 음함수 곡면 맞춤 기법(Implicit Surface Fitting)을 이용하여 모델의 꼭지점에서 곡률과 곡률 미분 값을 측정하였다. 이러한 방법은 다각형 모델의 꼭지점에서 음함수 곡면으로 정확하게 투영할 수 있도록 사용자의 정의 파라미타를 찾아야 하며, 특징 추출을 위한 많은 계산 시간을 요구한다. 그러나 제안 방법은 지역적 음함수 곡면 맞춤 기법을 이용하여 모델의 꼭지점에 근사된 곡면을 통해 미분 정보를 측정한다. 측정된 미분 정보를 통해 쉽게 각각의 모서리에서 제로-클로싱을 통해 특징 점을 추출하고, 곡률 방향을 따라 추출된 점들을 연결하여 특징 선을 생성한다. 여러 가지 다각형 모델에서 실험을 하였고 기존 방법보다 빠르며 높은 품질의 특징 선을 추출한다.

• 융복합기술연구소 논문집
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• 제10권1호
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• pp.7-12
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• 2020

We describe a efficient surface reconstruction method that reconstructs a 3D manifold polygonal mesh approximately passing through a set of 3D oriented points. Our algorithm includes 3D convex hull, octree data structure, signed distance function (SDF), and marching cubes. The 3D convex hull provides us with a fast computation of SDF, octree structure allows us to compute a minimal distance for SDF, and marching cubes lead to iso-surface generation with SDF. Our approach gives us flexibility in the choice of the resolution of the reconstructed surface, and it also enables to use on low-level PCs with minimal peak memory usage. Experimenting with publicly available scan data shows that we can reconstruct a polygonal mesh from point cloud of sizes varying from 10,000 ~ 1,000,000 in about 1~60 seconds.

• 한국컴퓨터그래픽스학회논문지
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• 제8권3호
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• pp.1-7
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• 2002

This paper presents a practical technique for approximating the boundary surface of the volume swept out by three-dimensional objects using the depth-buffer. Objects may change their geometries and orientations while sweeping. The sweep volume is approximated as a union of volume elements, which are just rendered inside appropriate viewing frusta of virtual cameras and mapped into screen viewports with depth-buffer. From the depth of each pixel in the screen space of each rendering, the corresponding point in the original world space can be computed. Appropriately connecting these points yields polygonal faces forming polygonal surface patches approximately covering some portion of the sweep volume. Each view frustum adds one or more surface patches in this way, and these presumably overlapped polygonal surface patches approximately enclose the whole sweep volume. These patches may further be processed to yield non-overlapped polygonal surfaces as an approximation to the boundary of the original 3D sweep volume.

• 복식문화연구
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• 제10권6호
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• pp.709-717
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• 2002

In the apparel industry, the technology has been advanced rapidly. The use of 3D scanning systems fur the capture and measurement of human body is becoming common place. Three dimensional digital image can be used for design, inspection, reproduction of physical objects. The purpose of this study is to develop a method that drafts men's basic bodice pattern from scanned 3D body surface shape data. In order to pursue this purpose the researchers developed pattern drafting algorithm. The 3D scanner used in this study was Cyberware Whole Body Scanner WB-4. The bodice pattern drafting algorithm from 3D body surface shape data developed in this study is as follows. First, convert geometric 3D body surface data to 3D polygonal mesh data. Second, develop algorithm to lay out 3D polygonal patches onto a plane using Auto Lisp program. The polygon meshes are coplanar, and the individual mesh is continuously in contact with next one The bodice front surface shape data in polygonal patches form was lined up in bust and waist levels. The back bodice was drafted by lining up the polygonal mesh in scapula, chest, and waist levels. in the drafts, gaps between polygons were formed into the darts.

• 한국레이저가공학회지
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• 제1권1호
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• pp.24-29
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• 1998

A new wide laser beam optical system for the laser materials processing has been developed with a polygonal mirror. It consists of polygonal mirror and cooling part that prevents the surface of rotating polygonal mirror from damage by heat. The polygonal minors have been designed and made as 24 and 30 facets in pyramid type. This system provides a uniform linear laser heat source with the surface scanning width from 15 to 50mm according to the scanning height To examine the wide laser beam, He-Ne laser is used. Also, Acryl is used to confirm the laser beam pattern by bum-pattern print To analyze the energy distribution of the wide laser ben empirical values and theoretical values are compared and discussed. To improve the efficiency of the wide laser beam optical system, methods are suggested by the optical theories. For larger area processing like turbine blade, drawing blade, cold roller and guide plate, optimal overlapping locations have been calculated and analyzed by geometric and optical theories.

• International Journal of CAD/CAM
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• 제9권1호
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• pp.71-77
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• 2010

Various applications, such as mesh composition and model repair, ask for a natural stitching for polygonal surfaces. Unlike the existing algorithms, we make full use of the information from the two feature lines to be stitched up, and present an accurate stitching method for polygonal surfaces, which minimizes the error between the feature lines. Given two directional polylines as the feature lines on polygonal surfaces, we modify the general placement method for points matching and arrive at a closed-form solution for optimal rotation and translation between the polylines. Following calculating out the stitching line, a local surface optimization method is designed and employed for postprocess in order to gain a natural blending of the stitching region.

• 대한산업공학회지
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• 제21권4호
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• pp.529-540
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• 1995

The paper deals with a procedure for constructing a composite surface interpolating a polygonal curve mesh defined from 3D scattered points. The procedure consists of a poly-angulation, construction of a curve net, and interpolation of the curve net. The poly-angulation contains a stage that changes a triangular edge net obtained from a triangulation into a poly-angular edge net. A curve net is constructed by replacing edges on the edge net with cubic Bezier curves. Finally, inside of an n-sided polygon is interpolated by n subdivided triangular subpatches. The method interpolates given point data with relatively few triangular subpatches. For an n-sided polygon, our method constructs an interpolant with n subdivided triangular subpatches while the existing triangular surface modeling needs 3(n-2) subpatches. The obtained surface is composed of quartic triangular patches which are $G^1$-continuous to adjacent patches.

• International Journal of Control, Automation, and Systems
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• 제6권5호
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• pp.713-721
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• 2008

This paper presents the robust velocity estimation of an omnidirectional mobile robot using a polygonal array of optical mice that are installed at the bottom of the mobile robot. First, the velocity kinematics from a mobile robot to an array of optical mice is derived as an overdetermined linear system. The least squares velocity estimate of a mobile robot is then obtained, which becomes the same as the simple average for a regular polygonal arrangement of optical mice. Next, several practical issues that need be addressed for the use of the least squares mobile robot velocity estimation using optical mice are investigated, which include measurement noises, partial malfunctions, and imperfect installation. Finally, experimental results with different number of optical mice and under different floor surface conditions are given to demonstrate the validity and performance of the proposed least squares mobile robot velocity estimation method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.787-792
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• 1996

The method of manipulation by striking a part and letting it slide until it comes to rest, has been very little studied. However, the manipulation method is not uncommon in our daily lives. We analyze the dynamic behavior of a rigid polygonal part being striked and sliding on a horizontal surface under the action of fiction. There are two parts in this problem; one is the impact problem, and the other is the sliding problem. We characterize the impact and sliding dynamics with friction for polygonal parts, and present the possibility of reverse calculation for motion planning of striking operations. Using a high speed video camera, the computer simulation results are experimentally verified.

• 한국정보과학회논문지:시스템및이론
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• 제34권12호
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• pp.641-655
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• 2007

컴퓨터 그래픽스를 비롯한 여러 응용 분야에서 3차원 다면체 모델에 대한 매개 변수화(parameterization) 기법이 중요하게 연구되어왔다. 매개 변수화에 대한 연구는 주로 3차원 다면체 모델을 2차원 평면으로 매핑 시켜주는 문제를 고려하는데, 이러한 매핑 과정에서 종종 다각형의 세밀한 형태를 제대로 표현하지 못하거나, 텍스처 매핑 등의 기법을 적용할 때 일부 왜곡이 발생하는 문제가 발생하고는 한다. 이러한 문제점을 해결하기 위해서 여러 가지 왜곡 처리 방법이 연구되었지만, 3차원 물체의 임의 영역에 대한 사각형 형태의 부분 매개 변수화(local parameterization)를 수행하기에는 종종 한계점을 가지고 있었다. 본 논문에서는 투영 등위 집합이라고 하는 수학적 도구를 사용하여 3차원 다면체 모델의 특정 지역을 효과적으로 매개 변수화 해주는 기법을 제안한다. 이 방법에서는 사용자가 지정한 임의의 영역에 대해 등간격의 곡선을 생성한 후, 이를 이용하여 사각형 형태의 영역에 대한 부분 매개 변수화 정보를 추출하는 방식을 취한다. 본 논문에서는 새로운 부분 매개 변수화 기법에 대하여 자세히 설명한 후 실험 결과를 기술하도록 한다.